hybridfree/eevblog-posts huggingface dataset:
Synchronous Buck capable of Sinking? - Page 1
Forum section: electronics / projects

author: bitbanger
author_rank: Regular Contributor
timestamp: January 19, 2018, 03:42:45 am
content: Hi Folks -I have a little "power ORing" conundrum and I'm curious: how do sync buck converter behave when asked to sink current? I'm sure this is largely controller specific so I'm looking at the LTC3621 (integrated switches) in particular.http://cds.linear.com/docs/en/datasheet/3621fc.pdfMy first guess was that it would try to regulate by keeping the bottom (NMOS?) switch activated, essentially dumping the inductor to ground (effectively "shorting" the regulator output to ground). However in reading the datasheet closer I'm not so sure (because it's partially regulating on inductor current as well as FB voltage). Especially interesting is in the section describing the "burst mode":"Thus, when the switcher is on at relatively light output loads, FB voltage will rise and cause the ITH voltage to drop. Once the ITH voltage goes below 0.2V,the switcher goes into its sleep mode with both power switches off. The switcher remains in this sleep state until the external load pulls the output voltage below its regulation point."Does this mean I can safely present a higher voltage at the output of the inductor? For my project I'm looking at the switcher (output variable between 4.5-7.4V) facing a potential fixed 7.5V.Another thought was that the regulator would "fall out of regulation", and perhaps I can finagle the PGOOD pin with the RUN to shut the regulator down? But then there's startup...hmm.Thoughts?Happy wiring,Jamie

author: Siwastaja
author_rank: Super Contributor
timestamp: January 20, 2018, 04:20:39 pm
content: Synchronous buck happily sinks if the controller allows reverse current. Some controllers prevent it.It works as a synchronous boost, injecting current into the "input", so you need input voltage measurement circuit to shut it down before the voltage rises too far to cause damage.

author: chris_leyson
author_rank: Super Contributor
timestamp: January 20, 2018, 05:01:41 pm
content: QuoteThe LTC3621 won't sink current, the bottom mosfet switches off when the current through it drops to zero if running in discontinuous mode or it switches off at the end of the switching cycle if running in continuos mode. There is a "reverse comparator" in the control logic that senses the mosfet current. Off hand I don't know of any synchronous buck controllers that will allow true synchronous operation and allow power to flow back from output to input. They're not hard to build though.

author: David Hess
author_rank: Super Contributor
timestamp: January 20, 2018, 10:54:46 pm
content: Quote from: chris_leyson on January 20, 2018, 05:01:41 pmLinear Technology has them under the DDR Memory/Bus Termination catagory:http://www.linear.com/parametric/ddr_memory|bus_termination
[Probably solved] Synchronous buck turnoff ringing seen as 200mV at output - Page 1
Forum section: electronics / projects

author: Whales
author_rank: Super Contributor
timestamp: July 29, 2025, 12:03:24 am
content: I recently built anAD6435224V-in 5V3A-out buck for a project at work. Its output seems quite noisy (200mV p-p high frequency hash) when loaded to about 50% powering a single board computer.Whilst investigating the output noise I added a few hundred uF of electrolytic capacitance to the output, this seemed to slow the switching freq down quite a lot and let me observe the following output voltage waveform (apologies for sketch, not in the office to get a proper capture today):I tried guessing some snubber values and adding those to the SW node but this didn't seem to reduce the ringing much or at all. Next I am going to try some small resistor values in series with the bootstrap capacitor and see if that helps.Question 1:The AD64352's switching speed is programmed by my 100 ohm resistor on its RT pin which should set it to 1MHz. Why did the AD64352 dramatically drop its switching speed when I added more output capacitance?From what I gather the AD64352 is a fixed-frequency peak-current-mode controller with an outer (internally compensated) voltage control loop.Perhaps there is some voltage hysteresis somewhere in the IC's internal circuitry? This would normally only serve to get rid of some noise & spurious behaviour issues, but in practice might also change the entire controller's behaviour to be hysteric-voltage-mode when the output capacitance is very large (or output load is very low)? This would explain the frequency drop.Question 2:Is it normal to be seeing 200mV of gate turnoff ringing on the output whilst under load? That feels excessive to me, but perhaps my expectations are too high?Question 3:Any thoughts on my layout?- I rotated the inductor the way I did to minimise the SW node surface area as much as possible. I assume the extra distance between inductor output & output caps is not as important, but I might be wrong.- 4 layer board with ground planes underneath.- The two FB resistors (R1 & R2 at top-left) are badly positioned, I think I should be sampling the voltage from nearer to the output capacitors instead of near to the output inductor. This noisy feedback sampling point, combined with the ringing, might explain why the voltage setpoint drops to about 4.9V under load.

author: Benta
author_rank: Super Contributor
timestamp: July 29, 2025, 12:15:00 am
content: Shouldn't RT be 100kohm?

author: Whales
author_rank: Super Contributor
timestamp: July 29, 2025, 12:28:46 am
content: Thankyou Benta. I had spotted the suffix 'k' on one side, not both.This means I'm running the chip totally out of spec and all behaviours are arbitrary.The datasheet mentions something about proprietary gate drive speed control:QuoteIf that circuitry thinks that I'm running the device way overspeed (by a factor of 1000) then it will probably overdrive the gates too, causing lots of ringing.
synchronous counter - Page 1
Forum section: electronics / projects

author: Abayomi
author_rank: Contributor
timestamp: September 09, 2016, 08:35:02 pm
content: Am trying to design a circuit that I will use one synchronous decade counter (74192) to control one 7-segment decoder(7447) . This decoder through a 1-4 demultiplexer is used to drive three 7-segments displays individually. The problem am now having is how to hold the voltages at each output of the demultiplexer when switching between outputs

author: Abayomi
author_rank: Contributor
timestamp: September 09, 2016, 09:39:15 pm
content: Any help please

author: MosherIV
author_rank: Super Contributor
timestamp: September 10, 2016, 09:16:42 am
content: There are 2 tecniques:1 latch the data/pattern into a buffer.2. Do the multiplexing so fast that the eye sees all 3 displays, relies on persistence of vision.For more/better help you will have to show a schematic of your circuit.

author: David Hess
author_rank: Super Contributor
timestamp: September 11, 2016, 02:49:02 am
content: Usually the multiplexer drives the 7447 with 4-bit BCD and the 7-segment displays are scanned. This works fine even with 8 displays and the multiplexer only needs to be 4 bits wide instead of 7 or 8 bits wide.
synchronous generator stator current question. - Page 1
Forum section: electronics / projects

author: Mehran
author_rank: Contributor
timestamp: May 24, 2020, 02:14:43 pm
content: been working on this question and I am totally stuck on the last part c(iii). I know the final answer is given in red but can't seem to get to it. Any ideas for how to get to the answer?

author: Vovk_Z
author_rank: Super Contributor
timestamp: May 25, 2020, 12:25:57 am
content: /off: I hardly can calculate (i) and (ii). It is about 20 years now since I have known something about electrical machines.
Synchronous motor pinout and run capacitor? - Page 1
Forum section: electronics / projects

author: profdc9
author_rank: Frequent Contributor
timestamp: May 02, 2020, 04:28:39 pm
content: I found the following motor on ebay that looks interesting for a project:https://www.ebay.com/itm/352546431397It says it is a two-speed motor, and there appear to be four connections to it. I would guess it might be something like this:http://www.seekic.com/circuit_diagram/Basic_Circuit/Single_phase_motor_two_speed_circuit_with_auxiliary_winding_connecting_to_tap_directly.htmlOne would be live connection, another would connect the capacitor, and two would switch the neutral between the two speeds. Is it likely to be true? Would there be a way to figure this out by measuring the inductance of the windings, and estimating the capacitance needed? Would a polypropylene capacitor work, perhaps of 3 microfarads or so. I would guess that the capacitance is pretty low given its low hp.

author: Benta
author_rank: Super Contributor
timestamp: May 02, 2020, 04:41:35 pm
content: The "two speeds" are because it's rated for 50 and 60 Hz. Induction motor, might have an internal cap, might not. Name plate does not give enough information.The wire connected to the housing suggests an earth connection, this could explain the 4-pole connector.

author: duak
author_rank: Super Contributor
timestamp: May 02, 2020, 05:43:55 pm
content: As Benta says, this is a motor that runs at a speed determined by the line frequency. I don't believe it is a synchronous motor where the RPM is exactly locked to the line frequency, rather, it is an induction motor where the RPM is lower and depends on the load. Do you need to vary the RPM?Here's a description of the general type:https://www.beckettcorp.com/support/tech-bulletins/an-introduction-to-psc-motors/You should be able to determine the two windings by their resistance. There is a type of the these called reversible PSC motors where the windings have the same impedance. In this case, it doesn't matter which winding is used as the main.Do you need to reverse the motor on the fly?Your run capacitor value is in the right ballpark. Polypropylene is a good choice. I would go for at least a 400 VDC rating.When it's all done, check the AC current to see that it's not higher than what is shown.

author: profdc9
author_rank: Frequent Contributor
timestamp: May 02, 2020, 05:58:30 pm
content: My main interest in the motor was to find a motor that can rotate an object (about 200 to 400 g) at approximately 1800 rpm, an object probably closed to balanced but not perfectly so, but the speed does not need to be precisely that value. I do not need to reverse the motor, but I would like the speed of the motor to be somewhere close to 1800 rpm and be relatively constant.I was considering a smaller DC brushed motor but I am not sure that a smaller DC brushed motor is heavy duty enough to hold a 400 g load steady and rotate it with some small imbalance. The motor I am looking at is probably a little overkill but it seems to be a good surplus find.
System DC PSU turned into a 2 channel SMU - Page 1
Forum section: electronics / projects

author: diegoperez
author_rank: Contributor
timestamp: April 27, 2016, 07:00:25 pm
content: Hi,I'd like to know if this idea may be interesting or viable.Could it be possible to write a program (using the GPIB) that gives the functionality of a semiconductor curve tracer or a source meter unit (smu) to a dc power supply like thishttp://www.ebay.com/itm/HP6625A-0-50v-0-50v-0-16V-DC-SYSTEM-Mains-Power-supply-with-HPIB-/301932242004?hash=item464c906454%3Ag%3AZKgAAOSw14xXE5Uj&nma=true&si=2zsEGr3U5lGQcmhoNlE3VhLtz1c%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557?The specs of this particular model can be found here page 16http://literature.cdn.keysight.com/litweb/pdf/06626-90001.pdf. They are pretty impressive: programming resolution 460uV and 1uA (in the lowest range).Indications, sugestions, or any comments would be appreciated.

author: Someone
author_rank: Super Contributor
timestamp: April 28, 2016, 12:17:44 am
content: It will work within its specifications, modern SMUs have several improvements over a traditional power supply:The outputs are bipolar without using relays to change polarity so you can smoothly sweep through 0VSettling times are much faster than traditional power suppliesCurrent source/measure will have multiple ranges to extend to much smaller measurementsSequencing and measurements are handled on the device so the host isn't timing everythingFully symmetric 4 quadrant capability
System for improved distancing at the VA - Page 1
Forum section: electronics / projects

author: Peabody
author_rank: Super Contributor
timestamp: October 20, 2020, 02:21:44 pm
content: It's time for my annual lab work blood draw at the VA clinic. I'll arrive, and take a number, then sit near 100 or so of my fellow veterans waiting for my number to be called. It may take 90 minutes before they get to me.I'm sure they are spreading people out better now, but I wonder if there might be a way for me to go sit in my car and follow which number is being called, so I can go back in only when I'm next. Currently, a technician opens the door to the lab area and shouts the next number to the waiting crowd.I had thought that a very low power FM broadcast of the audio at the lab door would work, but while my phone and car have FM radios, I don't know how common they are anymore. Then I thought maybe the audio could be streamed to some internet site that the patients could listen in on. But I don't know if that's practical. Then perhaps some kind of messaging service that the vet would sign up for temporarily, and the technicians would just enter the next number and it would be transmitted immediately to all subscribers. Or maybe just some kind of wifi thing to carry the audio.I would appreciate any suggestions for how this might be done. It would be better if it's something I could build or buy and set up for them so it wouldn't be bureaucratically impossible to implement. And of course it can't really take up any technicians' time since they are pretty overwhelmed as it is, and it has to be legal FCC-wise.

author: SuzyC
author_rank: Frequent Contributor
timestamp: October 21, 2020, 08:17:20 pm
content: Easy. Everyone has a smartphone and SMS capability. Every vet just gives the clinic their mobile number. The clinic simply sends the next in line a call or SMS when ready!
system level simulation software - Page 1
Forum section: electronics / projects

author: arjuna_m
author_rank: Newbie
timestamp: May 27, 2020, 03:20:24 pm
content: Greetings people,Has anyone come across *electronic system level simulation software in which one can do ideal component/building block level mixed signal simulation (similar to the diagrammatic building block style representation found in IC diagrams- say LTC3105 block diagram for example)easily?* I use mainly Simulink, alongside PLECS, SIMetrix/SIMPLIS, LTspice at the moment for system level simulation.SIMPLIS has a System-Designer which has components like ADCs DACs etc. but not a complete solution.I am no software guy, guess its not impossible to write a softwareany comments appreciated..

author: SiliconWizard
author_rank: Super Contributor
timestamp: May 27, 2020, 03:30:18 pm
content: Not completely sure what exactly you want to do. System-level simulation is a pretty generic term, and there's a lot you can do with something like Simulink already.If what you mostly need is to use reusable "blocks", but a mixed-signal simulator is OK, you can always create hierarchical blocks, that's something you can do with LTSpice, and many others. Using arbitrary voltage sources and current sources, there's a lot you can simulate that is not actually electrical, too.For something else, that can typically be used for "system-level" simulation, you could take a look at Modelica:https://en.wikipedia.org/wiki/Modelica
T2080: D_INIT FAILED Processor DDR Initialization failing - Page 1
Forum section: electronics / projects

author: LakshmiN
author_rank: Contributor
timestamp: October 06, 2023, 02:32:11 pm
content: HiWe are using T2080 NXP based Processor.We are facing an issue while bring-up of this Processor. D_INIT FAILEDDDR P/N: MT41K512M16VRP-107 AAT:PTo give an overview of implementation, Processor Power rails are controlled through Artix FPGA.Hence Artix FPGA will power ON First and Enable the Processor all rails and Processor is made out of reset, Once all the Power and clocks to Processor's are stable.FPGA Is controlling aswell as Monitoring the Processor's Power rails.After all Power and Clock Stable, POR_B Released from Processor and After 10us DDR_RESET is released.We connect to the GUI i.e., Code warrior through JTAG/COP Header, Processor is detected and Trying to run DDR/Clock centring Initialization Test,But When we try the DDR/ Clock centring test, We are getting an error displaying, DDR_INIT Failing,I'm attaching the NXP Forum Link for your reference for Register reads when this DDR INIT Fails,NXP Forum Link:https://community.nxp.com/t5/CodeWarrior-for-QorIQ/T2080-DDR-Validation-Error-D-INIT-failed/m-p/1727066I would welcome your suggestions.Thanks.

author: LakshmiN
author_rank: Contributor
timestamp: October 08, 2023, 08:51:09 am
content: Hi People,Awaiting for any of your suggestions.

author: LakshmiN
author_rank: Contributor
timestamp: October 12, 2023, 05:06:52 pm
content: Hello all,I request all to atleast look into this and suggest your thoughts on this
Würth power plate second source - Page 1
Forum section: electronics / projects

author: fcb
author_rank: Super Contributor
timestamp: October 09, 2013, 12:10:56 pm
content: I'm looking at using Würth power plate terminals on a design.http://katalog.we-online.de/en/em/Powerbuchsen_zweireihig/7461057Anybody got experience with/or can recommend a second-source of these?
Dave’s uSupply Battery Powered Bench PSU rev-C  - Page 1
Forum section: electronics / projects

author: gregfox151@gmail.com
author_rank: Contributor
timestamp: November 05, 2013, 10:36:51 pm
content: Hi all,I bread boarded a portion of Dave’s uSupply Battery Powered Bench PSU rev-C and I think I found a problem. (See attached) If the LT3080 does not have a current draw on its output (pin 3) of a least .5mA it will not stay in regulation. Dave added a LM334 to the output to keep it in regulation, but the problem is the LM334 operates only down to 1 volt, therefore as the voltage drops down below a volt the LM334 will no longer operate, and the LT3080 will be out of regulation (you can’t get it below ~2 volts)In the attached schematic I show the bread board, and I can only get it down to 2.4 volts even after grounding the set pin. Does anyone know how to keep it in regulation and get “0” volts as an output? Does this work for Dave?Will he ever produce this product?Thanks!

author: kizzap
author_rank: Unknown
timestamp: November 06, 2013, 04:18:04 am
content: If I recall correctly, it says somewhere on the datasheet that the current needs to be sunk to a negative rail for the thing to work correctly.-kizzap

author: minime72706
author_rank: Frequent Contributor
timestamp: November 06, 2013, 04:56:53 am
content: I vaguely remember the video blog he did regarding using a current source to ensure minimum load for regulation - did he address the issue? I think he did.I can't think of an ELEGANT solution off of the top of my head.

author: kizzap
author_rank: Unknown
timestamp: November 06, 2013, 07:00:51 am
content: From the LT3080 datasheet itself:Output VoltageThe LT3080-1 generates a 10µA reference current that flows out of the SET pin. Connecting a resistor from SET to ground generates a voltage that becomes the reference point for the error amplifier (see Figure 1). The reference voltage is a straight multiplication of the SET pin current and the value of the resistor. Any voltage can be generated and there is no minimum output voltage for the regulator. A minimum load current of 1mA is required to maintain regulation regardless of output voltage.For true zero voltage output operation, this 1mA load current must be returned to a negative supply voltage.

author: gregfox151@gmail.com
author_rank: Contributor
timestamp: November 06, 2013, 12:42:59 pm
content: Thank all of you for the reply. As you can see from the schematic, SET was grounded (0 volts). I decided to try other 3080s and on the third try it worked, bad batch.

author: minime72706
author_rank: Frequent Contributor
timestamp: November 06, 2013, 02:42:16 pm
content: Quote from: kizzap on November 06, 2013, 07:00:51 amDespite this, you can typically get VERY CLOSE to 0V without returning it to a negative rail.
Weird I²C Signals, or what is it? - Page 1
Forum section: electronics / projects

author: 128er
author_rank: Regular Contributor
timestamp: April 05, 2014, 02:43:14 pm
content: Hi,at the moment im probing some data from a ultrasonic level sensor. You can attach a control interface with LCD to it. It uses I²C between the two units (the manufacturer labled it as I²C). In the past i have probed some I²C lines, but this example is a bit weird. In the pictures you can see some analog-like artefacts. To hack into the signals, im using 8cm long wires for SCL, SDA and GND, which i have soldered onto LCD Unit. I can not imagine that it has any effects on the signal integrity (seen from my experiences in the past)I dont know whats going on thereBy the way: The devices are fully functional and do what they have to do

author: amyk
author_rank: Super Contributor
timestamp: April 05, 2014, 02:59:32 pm
content: Pullup resistors charging up the line capacitance. I2C is open-drain.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 05, 2014, 04:45:57 pm
content: That accounts for the rising edge of most, but what about the reeeeeaaaaaaalllly long edges sometimes seen?Agree, it's very strange. Maybe there are interface drivers in there, not just passive pullups?Tim
T7 transistortester dead from measurement - Page 1
Forum section: electronics / projects

author: repairMatthias
author_rank: Newbie
timestamp: June 17, 2024, 08:37:33 pm
content: A T7 transistortester died when trying to measure a desoldered discharged cap. What happened? First there came a message that no part could be detected. I disconnected leads and used 2 other socket pins which resulted in a discharge killing the T7, CPU dead. It seems to be that the tester itself charged the cap and when connecting to the other pins discharged, killing the CPU. With no schematic supplied I was unaware of the danger. Looks like the zener testing charged the cap. No zener detected, no cap detected. Then the tester destroyed because of reconnecting. Has anybody seen this happen?

author: Gyro
author_rank: Super Contributor
timestamp: June 17, 2024, 08:50:53 pm
content: It sounds like charge recovery. Dielectric absorption can cause the capacitor voltage to recover to some extent after it has been discharged. This recovery can be significant for a high voltage cap.
Big High End Subwoofer 20 – 100 Hz  - Page 1
Forum section: electronics / projects

author: max-bit
author_rank: Frequent Contributor
timestamp: November 13, 2016, 09:37:32 am
content: The project was created for a friend. Initially, there were attempts to buy the factory subwoofer, but finding a subwoofer with desirable characteristics as good prices happened after simply not realistic, came the time to design... Super Subwoofer.See more:http://www.rflab.pl/rflab_wp/2016/11/11/high-end-subwoofer-18-60-hz-eng/

author: Bloch
author_rank: Unknown
timestamp: November 13, 2016, 09:53:50 am
content: Looks great.I have been wrong before but is this some kind of marketing wank ?Quote

author: Seekonk
author_rank: Super Contributor
timestamp: November 13, 2016, 10:24:58 am
content: I remember the old (must be 50 years ago) Infinity 1001 put plumbers putty around the base of the cone to lower resonance.

author: max-bit
author_rank: Frequent Contributor
timestamp: November 13, 2016, 12:52:44 pm
content: Quote from: Bloch on November 13, 2016, 09:53:50 amsorry mistake translations

author: German_EE
author_rank: Super Contributor
timestamp: November 13, 2016, 02:59:45 pm
content: I have a friend who built a sub about this size but the walls were constructed of concrete. Flexing wasn't a problem but lifting it was!

author: max-bit
author_rank: Frequent Contributor
timestamp: November 13, 2016, 05:25:49 pm
content: But nicer to look wall eg marble

author: nctnico
author_rank: Super Contributor
timestamp: November 13, 2016, 06:01:55 pm
content: Many years (>decade) ago I also build a subwoofer but I built it into a side table so it is dual function.
T8 ballasts to run T5 bulbs? - Page 1
Forum section: electronics / projects

author: Airwalk1616
author_rank: Contributor
timestamp: April 13, 2019, 03:01:02 pm
content: Hey guys. I recently bought a lot of 5 - 2lamp X 36W T8 ballasts.I'm now beginning to realize that I'd much rather use T5 bulbs.So I've done a bit of searching here and there, but can't find the answers I need. Basically I've found that the instant start would lower the life of the bulb but these would only turn on once a day. But also, as long as wattage is correct, it's possible.So t5HO bulbs are 54 watts.How could I use one ballasts 2 outputs and another ballast using one, to get 108w to split amongst 2 t5 bulbs? Or even using 3 whole ballasts for 4?I'm just a bit lost on how it'd be wired and done right to work. So I thought I'd bring it to the expert big brain group ova here!I'd appreciate any feedback, guys. Thanks a million!

author: james_s
author_rank: Super Contributor
timestamp: April 13, 2019, 05:37:54 pm
content: You can't, just don't. Fluorescent lamps and ballasts must be matched, tubes of different types run at different currents, the cathodes are different, the voltage drop across the tube is different, they have different characteristics and that's why specific ballasts are sold. If you have T8 ballasts use T8 tubes, there is no advantage of T5 tubes without the special ballasts to drive them.

author: Zero999
author_rank: Super Contributor
timestamp: April 13, 2019, 06:19:37 pm
content: Yes, you need to change the ballasts to ones which is designed for T5. See if the seller accepts returns. If not, sell them and buy the correct ballasts.https://en.wikipedia.org/wiki/T5_retrofit_conversionA ballast puts out a certain current and voltage. As a general rule, thinner tubes require a lower current, but higher voltage for the same tube length. It might work with a T8 ballast, but it won't be efficient and could shorten the life of the tube.
TA1000PS - PSU for audio amplifiers with protection, sofstart and fan controller - Page 1
Forum section: electronics / projects

author: donpetru
author_rank: Contributor
timestamp: July 20, 2014, 01:08:16 pm
content: TA1000PSis afree projectthat wants to fill the need for electronic kits for complete realization of a high power amplifier.TA1000PS includes: a DC voltage protection on the output amplifier, speaker delay, fan speed control to cool amplifiers heatsinks and one output +/-12Vdc to power an audio preamplifier.Since the project is more than 1Mb, I attached a external URL:http://www.mediafire.com/download/exnn9vbz12c331d/TA1000PS+-+Power+supply+for+audio+amplifiers+with+protection%2C+sofstart+and+fan+controller+included.pdfThe software will be written in the microcontroller is attached below.From the construction point of view, as you will notice, the schematic TA1000PS is divided into:- A power supply circuit for audio amplifiers (includes a bridge rectifier and filtering capacitors = four pieces of 10000uF-100V);- One output +/-12V DC for the power relay = 24Vdc/20 or 30amps (including the related protections) and for the power external circuit, such as an audio preamplifier;- A circuit or a separate power supply, electrically isolated, to power two fans (one fuzzy controller with Atmel MCU (Attiny45) but you can also use Attiny85). The software MCU I will post below;- a filter on the 230 VAC supply.The software I can customize it, for example, if you want the DC fans to respond differently to various temperature thresholds. This is necessary because, in a certain situation, how fan speed variation with temperature may not be the most suitable. The cost will be a modest if you want only change temperature range (eg, $ 10).Noted that the above software has been designed on the following fields of temperature:- 0 ... 40 degrees C - speed 0, fan off- 40 .. 55 degrees C - about 40% of rated speed- 55 ... 70 degrees C - about 70% of rated speed- 70 ... 85 degrees C - nominal speed;- 85 degrees C - thermal protection on each channel amplification part (the fan runs at full speed). If the temperature drops below 85 gr. Celsius, the controller resumes normal operating cycle.Depending on the type of fan used can record small variations in measurements mentioned above. The project was designed to operate with 12VDC fans (max. 0.75A) but can be adapted (by change two resistors) and for 24VDC fans. Of course, the input power brigde voltage will be higher if you want to use 24VDC fans.For temperature measurement, I used two pieces LM35, one on each channel.This project has been tested and works flawless.P.S.Unfortunately, PCB's have not done because there was not enough users on my site to subscribe.I hope you enjoy this free project and if there are any questions, please ask in this thread.
Tab size? - Panelized PCB - Page 1
Forum section: electronics / projects

author: benjones
author_rank: Contributor
timestamp: December 25, 2014, 08:02:39 pm
content: Hey!I have my PCB designed and prototyped and I'd like to put in an order with Seeed Fusion Premium but I wasn't sure what size my tabs should be. I'd like to do something similar to how this PCB is laid out, so I can just use a pair of side cutters to depanelize.Here is a closeup screenshot of the tabs on my panel along with some info24x30mm boards (100mm x 100mm panels)0.8mm thick pcb (half standard)4 corner tabs2.4mm diameter routing bit0.2mm grid in EagleThe board doesn't contain any components and won't go through a pick and place machine, it's an adapter board.Anyone know what size i should make my corner tabs?Thanks!-Ben

author: Christopher
author_rank: Frequent Contributor
timestamp: December 25, 2014, 09:18:46 pm
content: 5 mm is a good sizeBut like you say it's not going through a pick n placehttp://blogs.mentor.com/tom-hausherr/blog/tag/mouse-bite/

author: benjones
author_rank: Contributor
timestamp: December 25, 2014, 11:15:13 pm
content: yeah 5mm seems kind of overkill, at least for this.I've never ordered a panel before and don't know how strong the tabs need to be. I don't want it to fall apart while they are handling, or milling it.Have you ever done corner tabs like the panel Dave is holding?

author: Psi
author_rank: Super Contributor
timestamp: December 26, 2014, 01:20:32 am
content: Might pay to check if your chosen PCB-house can do routing through plated through holes before submitting it. Some of them bitch at that.

author: benjones
author_rank: Contributor
timestamp: December 26, 2014, 01:41:58 am
content: Thanks for the heads up Psi,Seeed does do half hole process if you do their premium service, which I need anyway because they don't do routed panelized boards on the cheaper service.http://www.seeedstudio.com/service/index.php?r=site/PremiumPcbQuoteDo you think 2mm on the corner would be better for tabs? I want something I can easily depanel with side cutters. I'm curious as to how big Dave's corner tabs are. They seem pretty small.Thanks for the help,-Ben
Tact push button with cap 7-10mm overall height above PCB and 4-6 diameter cap - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: June 15, 2021, 09:50:06 pm
content: Hi,I have been looking everywhere for a 6x6 tact switch with a round cap 4-6mm in diameter but only 7-10mm overall height but couldn't find any that is SMD (Omron has various but are all through hole).Can you suggest any series that is similar but SMD?Thank you!
Tact switch under lexan overlay - Page 1
Forum section: electronics / projects

author: michaelym
author_rank: Regular Contributor
timestamp: May 05, 2014, 06:02:36 am
content: Does anyone have experience or is there any literature out there about the recommended design of a tact switch under lexan overlay.What i'm looking for is:Distance of the lexan from the actuator, actuator force, embossed/not embossed, Diameter of embossingThanks

author: SL4P
author_rank: Super Contributor
timestamp: May 05, 2014, 07:25:38 am
content: Yes - and it works well.I had 16 long-stem tact switches peeking up through the aluminium panel, just flush to the surface. menu/yes/no/arrow diamond etcThe alu panel was drilled (obviously), then a 10mmsemi-shearcreated what was effectively a countersink dish around each button head.The pre-printed mylar label film was simply stuck to the aluminium and the legends & buttons worked perfectly.I needed to use long-stem switches - because a 20x4 LCD was also in the mix - and everything needed support. Whatever will fit your dimensions.

author: babysitter
author_rank: Frequent Contributor
timestamp: May 05, 2014, 07:26:14 am
content: Hi,did that before. Embossing makes quite a difference (We used embossing for a frequently necessary key (User event) and no embossing for a kew which was to be used rarely (turn on/off bluetooth) on the same panel), used adjustable (PCB between two nuts on a screw, on 4 corners) PCB mount to get a good button feeling. We used bigger holes than the tact switch stem and put caps between the stem and the lexan film.
Tactile PCB button - Page 1
Forum section: electronics / projects

author: halexa
author_rank: Regular Contributor
timestamp: March 29, 2016, 07:25:01 am
content: Hi,Are there any tactile pcb buttons with the solder pads on the same side as the push button. See attached picture.My plan is to use a PCB as a front panel to an instrument I'm making and have the buttons mounted on the back of the PCB with a drill hole for the button.Or is there a better solution for PCB front panels and buttons.

author: ataradov
author_rank: Super Contributor
timestamp: March 29, 2016, 07:55:35 am
content: We discussed this not so long ago in another thread. There are no such buttons and it appears that this is intentional because mechanical stress will break solder joints.

author: halexa
author_rank: Regular Contributor
timestamp: March 29, 2016, 10:58:59 am
content: Quote from: ataradov on March 29, 2016, 07:55:35 amYes, after giving it some though it might not be a good ide. Might be better to stick with low profile SMD buttons.

author: ruffy91
author_rank: Regular Contributor
timestamp: March 29, 2016, 01:02:10 pm
content: A better solution in most cases when you want to use the PCB direct or with a glass or acrylic overlay is to use capacitive buttons.If you need tactile action consider snap domes (http://www.snaptron.com/products/dome-arrays/standard/).

author: halexa
author_rank: Regular Contributor
timestamp: March 29, 2016, 01:19:42 pm
content: Quote from: ruffy91 on March 29, 2016, 01:02:10 pmI want feedback on my buttons and these look like a perfect match for what I'm looking for. Thank you

author: Raj
author_rank: Frequent Contributor
timestamp: May 13, 2016, 07:29:38 am
content: how about these?http://www.sunrom.com/p/smd-tactile-switch-3x6x2-5mmI find them expensive so I don't use them.

author: charlespax
author_rank: Regular Contributor
timestamp: May 13, 2016, 07:43:47 am
content: Google for "adhesive dome switches". You would have exposed contacts on the PCB and place the dome switches over them. These dome switches can also be incorporated into membrane keypads.

author: matseng
author_rank: Frequent Contributor
timestamp: May 13, 2016, 02:35:56 pm
content: Quote from: Raj on May 13, 2016, 07:29:38 am1000 pcs for $54 in India. Whet I get a bag of them directly from China they are about $6 or 7 for 1000pcs.But still, 5 cents each is not that expensive - issit really?

author: Raj
author_rank: Frequent Contributor
timestamp: May 14, 2016, 11:38:50 am
content: :p it is since I use 2 resistors to forum a capacitive touch pad (for myself) or switches which costs 1$ for 100 pcs (for others)I hate corrosion
Tactile Switch Rating - Page 1
Forum section: electronics / projects

author: rstor22
author_rank: Regular Contributor
timestamp: April 11, 2015, 05:01:48 pm
content: Regarding the following circuit:http://electronicdesign.com/power/almost-ideal-low-battery-cutoff-circuit-draws-only-12-muahttp://electronicdesign.com/site-files/electronicdesign.com/files/archive/electronicdesign.com/files/29/4423/figure_01.gifIf I have a 1-2AMP load at the switched output, would the following tactile switch for S1 and S2 be adequate?:http://www.digikey.ca/product-search/en?KeyWords=b3f-1000&WT.z_header=search_goContact Rating @ Voltage 0.05A @ 24VDCI am unsure if I need a higher rated switch (i.e. 2A) as to my understanding once S1 is depressed the relay would be activated....Or do I need a switch rated for 2A for this circuit (based on the 1-2A draw at the switched output)?

author: zapta
author_rank: Super Contributor
timestamp: April 11, 2015, 05:28:35 pm
content: For a short time the switch will get the full rush current of the load. You can try decouple the power to the electronic circuit with a diode and then have the on switch powering only the electronics without carrying the load's current.
Tactile Switch vs Dome Membrane dilemma. - Page 1
Forum section: electronics / projects

author: alexg
author_rank: Regular Contributor
timestamp: January 23, 2017, 04:39:19 pm
content: Hi All, I am making a prototype of handheld device that need to have three buttons in a row and I am facing a dilemma what the best way to actuate them. I studied some TV removes, few other small devices out there and it seems like most of them using contacts directly on the PCB that are shorted with dome membrane that is pushed down by rubber button on top of it or with contacts being shorted by some kind of carbon stuff directly on the bottom of rubber bottom. I also really like small tactile switches like these here for examplehttps://www.digikey.com/product-detail/en/panasonic-electronic-components/EVQ-PLHA15/P8046SCT-ND/50173,they are easy to mount for me and they are dust resistant.I have a feeling that the best way is to have custom made dome membrane array of 3 buttons but my concern is that contacts underneath them can oxidize overtime.I really like tactile switch form the link above but not sure if this is some thing appropriate for the project just because I don't have experience designing keyboard for handheld devices.Basically, what would you suggest, membrane or tactile switch, considering that it need to be robust and have long life?

author: Ian.M
author_rank: Super Contributor
timestamp: January 23, 2017, 05:21:54 pm
content: Elastomer dome buttons are notoriously unreliable if used frequently over a long period. Remotes typically use carbon coated contacts on the PCB to get around the oxidisation issue. Better quality products have gold plated contacts on the PCB, but even so, you are likely to eventually run into problems with plasticiser migration forming an insulating oily film on the carbon loaded button contact surface.Another option is metal snap dome switches. Domes on a self-adhesive carrier can be stuck directly to the PCB and actuated by your choice of buttons, or even by direct finger pressure with a reinforced carrier, which can be silk screen printed with legends and other graphics and even embossed to tactilely define the buttons.

author: alexg
author_rank: Regular Contributor
timestamp: January 23, 2017, 08:05:04 pm
content: Yeah, I ditched the idea of making those buttons just rubber with carbon film just because I had some devices in the past that had keyboard bad and it was that kind of keyboard.So I am only bouncing between two choices now, metal dome over PCB contacts or an actual tactile switch assembly soldered to PCB. With metal dome it seems though I will need gold plating which will drive the cost of the board 5x times up, if only there was a possibility to do most of the board ENIG and then just the contacts for the metal dome gold plated.
tactile switch with 0.1" pin spacing? - Page 1
Forum section: electronics / projects

author: ralphd
author_rank: Frequent Contributor
timestamp: July 18, 2015, 09:58:58 pm
content: I'm looking for a tactile switch with 0.1" pin spacing to use for a RPi reset button. I have ones with 0.2" spacing that I could bend, but my preference would be something that fits unmodified.http://www.taydaelectronics.com/tact-switch-6-6mm-7mm-through-hole-spst-no-2904.htmlAnyone come across a part that fits the bill?
Tadirian TL5101 battery, I am impressed - Page 1
Forum section: electronics / projects

author: CaptDon
author_rank: Super Contributor
timestamp: September 28, 2024, 11:47:10 pm
content: I decided to open up my Alesis HR-16 drum machine to check on the memory battery. It is a TL-5101 dated 6/88. So it is about 36 years old. Still measured 3.74 volts!!! I bought a new one anyway. I compared some voltage drop reading under light load between the old battery and the new one and there is an almost un-noticable difference!!! The unit wasn't powered on for over 10 years and still had the old settings stored perfectly. There is no real time clock so I guess the static memory only drew a couple of microamps? Thank the power above that there wasn't the ni-cad 'creeping crud' syndrome!!

author: coppice
author_rank: Super Contributor
timestamp: September 28, 2024, 11:50:07 pm
content: There are a few companies trying to make extremely long life batteries now. We'll have to wait to access their success.Tadiran is the only one I know who has been doing it long enough to have an actual track record.

author: jbb
author_rank: Super Contributor
timestamp: September 29, 2024, 01:02:05 am
content: If I were making something like a defibrillator or rescue beacon, Tadirian would be my first step.But there are other manufacturers out there making the lithium thionyl chloride chemistry. At a previous job, we sourced pouch cells for backup batteries. These were much more convenient for manufacturing; we stuck them down with some 3M VHB tape, soldered the terminals down and then conformal coated over the top. That being said, we were only after a 5 year shelf life and no one would die if a unit didn’t last that long.

author: coppice
author_rank: Super Contributor
timestamp: September 29, 2024, 01:34:11 pm
content: Quote from: jbb on September 29, 2024, 01:02:05 amMost makes of lithium thionyl chloride batteries have multiple problems in long life applications. They usually won't specify anything beyond 10 to 15 years. They usually only show typical figures, and worst case can be all over the place. The data sheets usually only address self-leakage, and ignore external physical leakage. Lithium thionyl chloride batteries are better than most types for physical leakage, but some makes can be really unpredictable for it.

author: jbb
author_rank: Super Contributor
timestamp: September 29, 2024, 09:33:44 pm
content: Yeah, I think the cells we used were only specified for 5 or 10 year shelf life. I expect that very few companies offer specified life out past 10 years…
Tag-Connect headers are awesome. And evil. - Page 1
Forum section: electronics / projects

author: thm_w
author_rank: Super Contributor
timestamp: August 09, 2023, 10:03:15 pm
content: Its accepted that various manufactures use different pin orderings:https://github.com/KiCad/kicad-library/issues/1451but the fact they can't even standardize within their own product is just dumb.I guess they are hand soldered then overmolded? The IDC side stays the same in both cases.https://www.tag-connect.com/product/tc2050-idc-tag-connect-2050-idc

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 09, 2023, 10:11:49 pm
content: Yes I've used the TC2030 but had noticed the TC2050 is numbered completely differently.Always double check the datasheets.At least these are pretty simple footprints and the pin numbers are shown. I've had to deal with large connectors with no indication of the pins numbers on the footprint drawings - they were only shown on the mechanical drawing of the connector itself, and given the relatively intricate design of said connector, it required a lot of guesswork to get the footprint right. Major PITA.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 09, 2023, 10:23:13 pm
content: I once saw datasheets and photographs of an SMT LED in which at some time the Anode was marked, and form another batch (or type number) the Cathode was marked in the same way.You could see the difference on the LED's themselves by looking at the bonding wires through a microscope, but that was the only visible difference.There are a few good things that came from WW2. One thing we learned is that starting a war just to grab some land is obsolete, but not everybody got the message.Another good thing is that lots of things got standardized for efficiency.70 years later a lot of the then set standards are still in use (just go buy a standard metric drill for example, or anker chain, which is usually DIN766) but far too many things never got standardized. For example Microwave ovens all have the same type of tube, but they come in a gazillion different ways to mount, so spare parts are unobtanium or prohibitively expensive. Same with car tires. You can buy new tires, but there are far to many sizes for no valid reason at all. Nobody cares whether the rim is 10mm bigger or 20mm wider.(Phoenix makes their pluggable green screw terminals in both a 5mm and a 5.08mm pitch and those are not compatible, but I don't want to get sucked further into the Metric versus banana units today)
Tailed Vias in Eagle - Page 1
Forum section: electronics / projects

author: docu
author_rank: Newbie
timestamp: September 11, 2016, 05:05:41 pm
content: While watching the N64 teardown on EEVblog, I noticed that Nintendo used these interesting "tailed vias", where the trace does not dead end at the via, but rather opens up to surround the via. See the via directly above the "VI (+12V)" silkscreen text.Is it possible to achieve this using Eagle?On a side note, those curved traces are just beautiful!

author: Dave
author_rank: Super Contributor
timestamp: September 11, 2016, 05:12:32 pm
content: These are known asteardrops.You should be able to make them in Eagle as well.

author: Niklas
author_rank: Frequent Contributor
timestamp: September 11, 2016, 08:25:15 pm
content: I have not used Eagle for a couple of years, but last time I used it the teardrops function was a ULP that was executed when the routing job is finished.

author: amitchell
author_rank: Regular Contributor
timestamp: September 11, 2016, 09:59:31 pm
content: Yup teardrops.ulp just tried it out, thanks.

author: docu
author_rank: Newbie
timestamp: September 11, 2016, 10:15:32 pm
content: Quote from: amitchell on September 11, 2016, 09:59:31 pmCan confirm, this does appear to work.Found this for Altium, as well:Wish Eagle had this support natively built in! Also, the tear drops appear to be linear-only (not curved) and only apply to Vias. I had pad support turned on as well, but it did not seem to do anything.