hybridfree/eevblog-posts huggingface dataset:
Trap dipole for 40 80 160 - Page 1
Forum section: electronics / projects

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: June 06, 2021, 11:33:14 am
content: Hi,I wanted to build a trap dipole.Since i cant find any DIY projects I wanted to know how to design One.The traps I Will make would be made out of coax, and how do I measure them with a VNA?I do and S11 and how do I terminate the other end? Or use an S1-2 function and check at what frequency It resonate? And what test set I have to make to do that measurements?

author: bob91343
author_rank: Super Contributor
timestamp: June 06, 2021, 05:11:36 pm
content: What will your traps look like? You can design traps for each band but it depends on how you want to do it.

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: June 07, 2021, 08:57:53 am
content: Done One trap for the 10mOnly thing Is that It resonates differently of I flip It on the other side.I managed to make the values closer but the are off by a Little.I wanted to cover the FM part29.510 29.590 In FM repeaters29.610 - 29.690 out FM repeater aIt doesn't seen too bad
Traps for HF antenna - Page 1
Forum section: electronics / projects

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: June 09, 2021, 05:56:12 pm
content: Hi,I designed some traps for the 17mt band as a test.Since I never designed One, are they decent enought?I measured with an indirect measurement (coil) S11Both sides of the trap.

author: bob91343
author_rank: Super Contributor
timestamp: June 09, 2021, 09:50:28 pm
content: Are these traps intended to pass, or reject 17m signals?For pass, they need to have low impedance at the intended frequency. For reject, high impedance. This, relative to the impedance at the point of connection. They must also be able to withstand the rf currents as well as not break down when rf potential is large.

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: June 09, 2021, 10:44:26 pm
content: They are intended to let pass the 17m band.Also as coax trap have low q they dont build up top much voltage.

author: bob91343
author_rank: Super Contributor
timestamp: June 10, 2021, 04:25:33 am
content: Low Q means lossy. There is probably an optimum Q for the application that gives adequate bandwidth without serious loss.

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: June 10, 2021, 11:15:36 am
content: The Q Is low compared on the ones made with other Coaxial cables.Its around 150 ish Q
Trasnformer feedback winding  magnetic flux behaviour - Page 1
Forum section: electronics / projects

author: gkmaia
author_rank: Frequent Contributor
timestamp: September 21, 2019, 06:52:12 pm
content: If you look at the schematic bellow you will see T460 is a high frequency high voltage transformer.On T460 the primary winding 4-5 receives 120VDC from the mains transformer. The feedback winding 3-6 switches Q458 on and off and that allows the primary to generate magnetic flux.What I am curious to know are the physical/electrical principles that causes the feedback winding magnetic flux to start/collapse and turn on/off Q548.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: September 22, 2019, 01:14:32 am
content: Hello Sir GKmaia,Recently I am doing similar project on a Class D amplifier used to run a potential and a current transformer.The transformer input and output impedance need to be calculate. Interesting to see its " phase shift" behavour at high or low frequency.People also curious about" core saturation" effect."A product with a Class-D audio power amplifier (APA) driving an output transformer with inadequatelow-frequency performance may shut down when its output is stepped from zero to maximum at the start of a sine cycle. Shutdown is triggered by short circuit protection (SCP), after the first half cycle of the sine output. The root cause is saturation of the transformer core."
Treadmill driver reverse engineering and Arduino fitting  - Page 1
Forum section: electronics / projects

author: geshka
author_rank: Regular Contributor
timestamp: January 10, 2024, 07:30:42 pm
content: Hello team.I recovered treadmill driver "Jonson fitness" and control panel with feedback loop. It works quite nice on my lathe with 2HP DC motor - keeping speed and counteracting load. The only issue is the control panel from treadmill that looks big and silly mounted on lathe. I am trying to get rid from that panel and retrofit Arduino board. I found nice solution for MC2100 , however I don't have any schematics my driver.I am trying to watch signals form control panel to the driver board but there is no ground on the board and I afraid to connect scope to it . Looking into driver board I noticed that it has topology of the SMPS. There is an isolated part of the driver that is "talking" to control panel. On the picture - it is divided by blue line, transformer wounds marked as red, plus and minus in black. What if I will ground that "floating" minus of the isolated part of the driver?

author: geshka
author_rank: Regular Contributor
timestamp: January 11, 2024, 09:03:13 pm
content: Some update...I was able to connect local minus (area segregated with blue line) to the mains ground and safely connected scope to it. Here are the signals on connector from that area which is going to the control panel.1. Up - used for incline/decline. Not interested2. Down - used for incline/decline. Not interested3. Ground4 Plus 15V5. PWM signal from control panel to the motor driver freq. 250 Hz. Duty width of the signal is something strange , need to be investigated further.6. No signal7. No signal8. Signal from tacho sensor from power board to the control panel9. Plus 5VRegarding PWM from control panel to the driver - as I mentioned - quite weird. at this moment what I see is the constant duty cycle about 50%, however during the speed change from control panel it wider or narrower (depends on requested speed) and then, when speed is established, PWM is getting back to 50%. Weird...

author: electro_lex
author_rank: Newbie
timestamp: November 12, 2024, 07:33:05 pm
content: Hi Geshka,Thanks for posting this info. I have the same board and I want to drive it with a micro controller.Did you end up figuring out the PWM control signal on pin 5?Does the duty cycle vary the motor speed or is it more complicated than just PWM? What is the PWM signal peak voltage?
Treadmill motor and KBIC-120 - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: August 06, 2021, 04:26:07 pm
content: I have a treadmill motor rated 135Vdc, 18.8A, 2.75H.P. 3950 RPMI want to use this for two things 1) a flapper disk sander for cleaning up the edges of just machined metal, and tool grinding with a diamond disk so fairly slow speedI can get a KB electronics KBIC-120 for about $30, so the price is right, however this is only rated for 1HP, 12A @90Vdc.https://www.galco.com/techdoc/kb/kbic-120_dat.pdf1HP should be more than adequate from a power to the wheel perspective, I'm just not sure how the drive will respond to a motor larger than it's rating when lightly loaded?Anyone try this?Words of wisdom?I also have the original motor driver board, however no schematic, so other than kludge PWM to output FET stage I think that's a loss.

author: jpanhalt
author_rank: Super Contributor
timestamp: August 06, 2021, 04:53:07 pm
content: I would be worried about starting current. The KBIC-120 does have programmable start:QuoteSo, give it a try. Also, the current sense resistor can be reduced a little, but then you may cause other problems.The datasheet shows a 0.5 HP continuous rating without a heatsink:

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 07, 2021, 01:49:04 am
content: Easiest way to reuse the motor is to connect it to a rectifier with a universal motor speed controller to adjust it.

author: WattsThat
author_rank: Frequent Contributor
timestamp: August 08, 2021, 03:48:39 am
content: The drive will not care so long as you don’t exceed its current rating. What usually gets overlooked is the reduction in available horsepower when you slow down a motor. You’ll be dealing with two de-rates, one for speed and one for the reduction in torque due to the lower drive amp rating.With your example motor, let’s say you run it at 30 volts. Speed will be 30 /135 * 3950 = 878 rpm. At that speed, if you load it to the drive rating (with a heatsink) of 12 amps, the available HP would be:12 /18.8 * 30 / 135 * 2.75 = 0.39 HP
Tremolo control - input signal seems to be riding the output - Page 1
Forum section: electronics / projects

author: atferrari
author_rank: Frequent Contributor
timestamp: February 05, 2015, 06:08:37 pm
content: PROBLEM SOLVEDLTSPICE - .asc file, model and sub attached.In this basic tremolo control, I cannot avoid what seems to be the input signal riding the output.As is, even if the JFet is cut (??) I still get the equivalent of the input signal, at the output.Sure it is more than 100% modulation; done on purpose to put in evidence that the JFet is cut.Around this for many hours, I supose I am wrongly biasing the opamp but cannot see where or how.Comments will be appreciated.
Triac Activation - Page 1
Forum section: electronics / projects

author: maurosmartins
author_rank: Regular Contributor
timestamp: December 19, 2017, 05:14:32 pm
content: Hello all,for a project that I'm starting I need to use triacs to dim lights. After searching I've found two variations of the circuit using an optocoupler, please see image below:my doubt is in the circuit on the right and relates to the R1 and C2 network, what is the advantage of using this type of circuit instead of only an resistor just like the circuit on the left? the gate current is different in one case and the other, but the final result is the same:Looking forward your reply,Best regards, Mauro.

author: schmitt trigger
author_rank: Super Contributor
timestamp: December 19, 2017, 05:27:54 pm
content: If your load is purely resistive, then you don't require those snubber components (R1, C1).

author: floobydust
author_rank: Super Contributor
timestamp: December 19, 2017, 09:38:00 pm
content: It's in a old Motorolaapp note AN3003on driving TRIACs.The extra R1C1 adds a phase-shift needed for inductive loads. I thought it also gives higher peak gate current to turn on the TRIAC harder, and then fall to a lower holding current.Your gate drive circuit all depends on your load, and TRIAC selection- sensitive gate or three quadrant type.In your sims, I'd have the MT1-G resistor to lessen sensitivity to dV/dt; 330R-1k.

author: Circlotron
author_rank: Super Contributor
timestamp: December 20, 2017, 07:24:28 am
content: Without this dc combination you are limited in how close to the voltage zero crossing you can fire the triac because right at the zero crossing there is no voltage available to the gate! With the rc the voltage across the capacitor lags the main voltage so there is still some voltage across it at zero crossing so you should be able to conduct the full 180deg if necessary.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 20, 2017, 07:29:33 am
content: It's a noise immunity precaution, so that mains dV/dt isn't coupled directly into the gate by the opto's off-state capacitance. This is more important for sensitive-gate TRIACs.If the time constant is relatively large (comparable to the mains period), the phase shift will be noticeable as well, giving the above mentioned features.Tim
TRIAC as switch for Transformer. - Page 1
Forum section: electronics / projects

author: aksal60
author_rank: Newbie
timestamp: August 22, 2016, 07:56:00 am
content: I need to use a relatively low current 240Vac on/off switch for a 1000va transformer and have been wondering on the possibility of using a TRIAC for this .This is for a power amplifier.I dont have a seperate AUX power supply so obviously a relay is not possible.I think some amplifier designs ( Peavey i think?) in the past have used a similar configuration although im not sure.Could this be a practical idea?

author: Kjelt
author_rank: Super Contributor
timestamp: August 22, 2016, 08:02:33 am
content: Delta (Holland) used this in their power supplies AFAIK, when the output voltage was relatively low they switched/dimmed the input voltage with the triac, so to keep the losses in the linear regulators low.However to control the triac they seem to have an aux. powersupply (extra transformer).For audio amplifiers I am curious how you are going to filter the switching noise ?

author: MosherIV
author_rank: Super Contributor
timestamp: August 22, 2016, 09:11:52 am
content: QuoteI believe it can work.I am not an expert with TRIACs or SCRs, I am still learning myself.I know that TRIACs only work on 1 half of AC wave, so you will need 2, one for each half oruse a SCR, they work on either half of sine wave.You can get opto coupled SCRs or there are some SCR that are 5V logic level for the trigger.

author: Zero999
author_rank: Super Contributor
timestamp: August 22, 2016, 09:25:09 am
content: Quote from: MosherIV on August 22, 2016, 09:11:52 amYou've got that backwards: SCRs are unidirectional and only work on one side of the sine wave, TRIACs are bidirectional and work on both positive and negative currents.https://en.wikipedia.org/wiki/TRIAChttps://en.wikipedia.org/wiki/Silicon_controlled_rectifier

author: kmossman
author_rank: Contributor
timestamp: August 22, 2016, 10:10:43 am
content: As long as you are using it as a on/off switch, no problem

author: Cyberdragon
author_rank: Super Contributor
timestamp: August 22, 2016, 10:17:48 pm
content: There are also quadracs which are triacs with an integrated diac on the gate.
Triac Circuit with Voltage Divider. - Page 1
Forum section: electronics / projects

author: Bskitter
author_rank: Regular Contributor
timestamp: November 09, 2017, 06:53:28 pm
content: Hello People.I have a question here, but first a little background story. I have an SMD station that lost its magic smoke a while back. So I made a little project to fix it. I am basically redoing all the electronics inside.I have basically complete the interface for it (The Temperature display and Pot readings) I am now doing the power control circuit for the Air Pump and Element Control...So here is the question. On the old circuit there was a Bridge Rectifier on the output of the triac going to the pump. After a lot of searching and asking my Professors at the university I found out that this Rectifier acts as voltage divider for the inductive load.Below is the schematic.Now here is the new circuit ill be using to control the Pump.I am gonna use the Microcontroller to control the speed of the motor.Now. How do i connect the bridge rectifier to the Optocoupled circuit ?I am thinking of something like this.Any suggestions would be appreciatedByron

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 09, 2017, 08:08:51 pm
content: The arrangement with the diodes improves control at low levels. It is not needed with a SSR.http://techno-fandom.org/~hobbit/lighting/dimmer.html

author: Benta
author_rank: Super Contributor
timestamp: November 09, 2017, 11:16:07 pm
content: As far as I can see, the bridge rectifier in your first schematic doesn't do anything at all. Have you oriented it correctly?

author: Andy Watson
author_rank: Super Contributor
timestamp: November 09, 2017, 11:45:41 pm
content: Quote from: Benta on November 09, 2017, 11:16:07 pmIt removes a "hysteresis" effect at low power settings by returning the timing capacitor voltage to zero each new half-cycle. The link that NiHaoMike provided explains the problem.
Triac control - 1 or 2 resistors? - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: July 25, 2020, 08:23:27 pm
content: Hi,with reference to the attached pictures, to enable the TRIAC some circuits use only one resistor between gate and one of the terminals and other circuits use two resistors (one between gate and one terminal and another between gate and the other terminal. Why do some use one and other use 2 resistors? Any pros and cons to each solution?Which is correct?Also I assume that T1 and T2 are fully swappable correct?Thank you

author: Zero999
author_rank: Super Contributor
timestamp: July 25, 2020, 08:36:29 pm
content: You forgot the attachments.

author: ricko_uk
author_rank: Super Contributor
timestamp: July 25, 2020, 09:12:49 pm
content: Oops, attached now

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 25, 2020, 11:15:34 pm
content: Wat is an T1 and T2The A1 and A2 terminals of a triac are NOT interchangeable.An image search reveald they're somtimes also called "MT1" and "MT2", maybe other names too. But still, they are not interchangable.In the schematic with the MOC3021 and the BT136 you only have a resistor to limit the trigger current.In the schematic with the MOC3061 and the BTA41 you also have a resistor to lower the sensitivity of the triac.Why do you think (assume?) these different components would work in the same schematic?The values of the snubber network are also different between these schematics.When looking at some pictures I saw this:http://www.penguintutor.com/It shows clear differences between the MT1 and MT2 terminal.Ah, the resistor...Whether you need (or are wise to) use the extra resistor depends on a lot of things.Simple answer is, sometimes it's needed, and it almost never hurts to put it in.Main factors are the leakage of the Opto Triac, minimum sensitivity of the big Triac, dU/dt stuff, leakage over (old dirty) PCB's and probably more.

author: Zero999
author_rank: Super Contributor
timestamp: July 26, 2020, 11:45:52 am
content: Both of the schematics are posted are correct, as mentioned above the gate-T1 resistor is there to reduce the TRIAC's sensitivity, thus making false triggering from any leakage current through the opto-TRIAC unlikely.T1 and T2 aren't interchangeable. The TRIAC's gate is referenced to T1. If you connect the gate to T2, via a resistor, it will always be on, whilst if the gate is connected to T1, it will always be off. The TRIAC is triggered when the gate is more positive/negative, than T1.

author: ricko_uk
author_rank: Super Contributor
timestamp: July 26, 2020, 05:03:04 pm
content: Thank you Zero999 and Doctorandus_P !
Triac control system for soft start - Page 1
Forum section: electronics / projects

author: Anja
author_rank: Newbie
timestamp: November 21, 2022, 12:29:36 pm
content: Hello,I built a circuit in LTSpice in order to come up with a control circuit for the triac, which is designed to limit the current flowing to the receiver (which is the power supply), and without which there is an overvoltage that stops the voltage flow.The plan is to design a triac control system that limits the current to 10 A but I don't know how to approach that.The initial approach of applying a behavioral source of tension led to the analysis shown in the PDF document, which shows that this approach really has no effect.What ideas do you have for the analysis circuit for LTSpice? I thought that the triac would control the zener diode, but I have too little experience to figure out how to work efficiently.I am asking for help in inventing a system with a triac for soft start, so that a current of 10 A is constantly flowing to the receiver.I am asking for help in inventing a system with a triac for soft start, so that a current of 10 A is constantly flowing to the receiver.In the picture you can see a red rectangle and this is where you need to come up with a control system for a variable resistance load.Best regards,Anna

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 21, 2022, 01:45:25 pm
content: You can't limit the current with a triac, only works in off and on state, it's not a transistor, there's no way you can it use in linear mode!It can only chop the AC wave, but once triggered it'll stay in conducting state, you can't switch it off (It's a latching device), the only way is to let the current drop enough so it releases itself, this is why it's only used in AC, the zero voltage crossing releases it.Wave chopping operation (The red wave would be the voltage at the load):Get yourself documented about how triacs work:http://tahmidmc.blogspot.com/2013/07/ac-power-control-with-thyristor.html

author: Brianf
author_rank: Regular Contributor
timestamp: November 21, 2022, 03:43:05 pm
content: What's your load? One usual technique for soft start is to have a series resistor which, after a time delay, is bypassed by a relay or triac.

author: jonpaul
author_rank: Super Contributor
timestamp: November 22, 2022, 07:13:34 am
content: Triac will cause issues on inductive or transformer load.Simple soft start is a series NTC thermistor, perhaps $0.50Why do you need a soft start?What is the load type, V, VA/KVA?Jon
Triac control using PWM  - Page 1
Forum section: electronics / projects

author: NASK
author_rank: Contributor
timestamp: December 04, 2017, 06:33:26 am
content: I need to speed control a single phase AC motor by using Triac. Therefore I need to trigger the triac gate using PWM pulse. Here I draw sample circuit & test changing the pulse width but I couldn’t take proper triggering shape. I thing solution is Zero Crossing circuit but how design it for this sample circuit .

author: fcb
author_rank: Super Contributor
timestamp: December 04, 2017, 08:59:25 am
content: Aside from a load of questions regarding theactualtype of AC motor, you should read up on TRIAC triggering modes and techniques - it's really well worth getting your head round how they actually work.

author: Zero999
author_rank: Super Contributor
timestamp: December 04, 2017, 10:47:51 am
content: PWM is not used for TRIACs driving motors. It would require a much lower PWM frequency, than the mains frequencyPhase control is used, which is a totally different thing. A TRIAC is a latching switch and only needs a brief pulse at the gate to turn on, then it will remain on, until the AC cycle passes through zero. Phase control works by delaying the gate trigger pulse, for a certain length of time after the zero crossing point. The greater the delay, the lower the power.What sort of motor is it? How is it being used?Phase control is only really good for brushed universal motors. It it not suitable for induction motors, unless they're used to drive a light load, such as a fan. A variable speed drive, is the correct way to control the speed of an induction motor.

author: danadak
author_rank: Super Contributor
timestamp: December 04, 2017, 12:28:35 pm
content: https://www.ab.com/support/abdrives/documentation/techpapers/DriveMotorBasics01.pdfhttp://www.ecmweb.com/power-quality/basics-variable-frequency-driveshttp://www100.abb.com/Drives_DE/fundamentals/basics/dc_drive_basics_01r0201/data/downloads/dc%20drive%20basics%2001r0201.pdfhttps://www.google.com/search?q=motor+drive+basiscs&oq=motor+drive+basiscs&aqs=chrome..69i57j0l5.5628j1j4&sourceid=chrome&ie=UTF-8Some useful ref material.Regards, Dana.

author: NASK
author_rank: Contributor
timestamp: December 06, 2017, 03:32:44 am
content: Thank you for the support! I think finally I am able to design the requirement and it wish to use for small Ac motors. Hear attached results & used circuit.
TRIAC Doesn't Turn Off in LTSpice Simulation [SOLVED] - Page 1
Forum section: electronics / projects

author: Mezzer266
author_rank: Contributor
timestamp: February 21, 2018, 03:47:04 am
content: Hey everyone,So I'm trying to use a TRIAC to turn on 240V mains to a purely resistive load. I'm using a spice model for the Q6025N5 from "Little Fuse" in my analysis and I thought I would just throw together a quick test circuit to see if the import of the part worked correctly. So this is the point where I'm going to let you know I'm brand new to using TRIACs and I thought I understood how they functioned but it would seem not... I can get the part to work if I have the TRIAC hooked from 120V mains to GND, but as soon as I use two 120V supplies to create 240V, the way I would think it would get connected in real life here in the US, I not only get the part not turning off, but it will always stay in conduction despite the signal being high or low. Is there something I'm missing about the operaton of TRIACs that I'm missing or some other simple thing that would cause this?Circuit and Waveforms Below,Mezz

author: Mezzer266
author_rank: Contributor
timestamp: February 21, 2018, 04:14:53 am
content: Wow, can't believe I missed that. Thanks for the quick response.Mezz
Triac failure in homebrew heating mantle control - Page 1
Forum section: electronics / projects

author: subunit
author_rank: Contributor
timestamp: January 12, 2018, 10:42:39 pm
content: Hello- as my first "real" AC project, I decided to try building my own adjustable AC power controller for a couple of surplus Glas-Col heating mantles I have on hand. The OEM controllers are expensive and rare, so I figured I'd take a crack at a "budget" version using 4 modules in a plastic enclosure. I'm using-scraped 10A fused switch-eBay pot-adjustable Triac circuit (same one as Big Clive-)-eBay power factor meter - (this type:https://www.ebay.ca/itm/AC80-300V-100A-Digital-LED-Current-Voltage-Meter-Power-Factor-Detection/132273795146?hash=item1ecc21f04a:g:lxMAAOSwZB9aJjoB)-Hubbell GFCI outlet (https://www.zoro.com/hubbell-wiring-device-kellems-45ue94-gfci-rceptclecommer15a05-hp/g/00484955/)I wired these up as indicated in the attached circuit diagram (sorry for MS paint quality). Ibelieveboth pots on the triac board were set to zero resistance before i did anything. When I plugged the enclosure in and turned on the fused switch without the GFCI having been set up yet (must reset it with powered connection to complete the circuit), everything looked normal to me- the PFM read ~120V AC and 0 current. I plugged in one of the heating mantles and reset the GFCI, which immediately resulted in the Triac letting the smoke out (see attached photo).Anyone know what happened? Is it because I started the triac pots out on the low end, or am I missing some necessary component?

author: floobydust
author_rank: Super Contributor
timestamp: January 13, 2018, 10:51:13 pm
content: I would say the triac died from overcurrent, so your wiring is probably wrong (short circuit/gnd fault through PF meter or GFCI). Check with ohmmeter first! Then to test things, run this all with light bulbs, for the load or in series with input power.The Power Meter needs mains power and its input is referenced to neutral, so if you got that backwards then a short exists.The GFCI should be first because it needs stable 120VAC power, and you are feeding it phase-controlled pulses which will not work.Your heatsink could be hazardous live, if it's not an isolated-tab triac. A bigger pic would help.

author: subunit
author_rank: Contributor
timestamp: January 14, 2018, 12:05:41 am
content: Thanks for the pointers, floobydust!! I didn't realise the GFCI outlet wouldn't function downstream of the triac. I will need to try a different design and test things more carefully as you suggest!
TRIAC on a Secondary, RC snubber, and other protections - Page 1
Forum section: electronics / projects

author: Feliciano
author_rank: Frequent Contributor
timestamp: October 14, 2018, 03:16:15 pm
content: I have a Chinese single-side through-hole power control board made with Chinese generic parts. It's a thermostat-like controller.Some other people has reported several blowns of the board and/or the load. I think it's related with possible several hundred Volts spikes/transients due its lack of protection and bad manipulation (remove the load when live). To prevent that ever happens to me, I want to improve the circuit by adding some protections. In my country, forget about parts from the 21st (not even a MOV), so I'm working a solution with just few discrete traditional components.I add a simplified schematic of the critical subcircuit, with some modeling of somebody connecting and disconnecting the load live, or having attached a SMPS module to it.Is there a more effective way to achieve/improve this protection with low-tech parts?
Triac optocoupler problem - Page 1
Forum section: electronics / projects

author: Larry80
author_rank: Contributor
timestamp: December 13, 2018, 05:04:44 am
content: Hello,I have been wondering about specific triac circuit schematic, with random trigger (MOC 3021 etc.) triac optocoupler. This schematic is from the generic datasheet (attached) and widely adopted it seems.What is the purpose of the capacitor, i have not been able to find any specific information? Its somehow connected to the Igt requirement. Problem is that this type of circuit connection creates very high current pulse (1.5A) trough the 180ohm resistor when triac is turned on at the peak wave as the charged capacitor is rapidly discharged to the gate of the triac, plus it will dissipate about 1W of power vs. 0.5W that would occur otherwise (reduce footprint/BOM by wide margin) of this particular resistor. This seems to also create unnecessary EM radiation too..Edit: I found a Fairchild AN–780A which discusses the selection. Purpose is snubbing the optotriac, there must be a better solution.

author: Larry80
author_rank: Contributor
timestamp: December 13, 2018, 05:27:03 pm
content: I did modify the circuit as pictured. The main problem for increasing the resistance is the full duty-cycle turn on time. The increased delay is about 60uS and 15 Volts, when 1.2k resistor is used. This is also why you also cannot use the original circuit with both resistances at 1.2k (series resistance being 2.4k) as the only source for energy at 0 angle has to come from the line, not from the capacitor.Noticable reduction of audible switching noise and power levels at the resistor went to 1/4W from the original 1W. I guess the EM noise is also reduced a lot, but have not yet measured it.
Triac power switch design with less components - Page 1
Forum section: electronics / projects

author: s1m0n3t
author_rank: Newbie
timestamp: September 13, 2018, 10:51:27 am
content: Hi all,I'm trying to design a very compact AC switch, using a microcontroller and a triac. I would like to handle up to 16A (@230V), but a 16A relay is too big for my available space...I'm starting from a standard design, with an optotriac, that drives a power triac and it works, but it requires many components, including the optotriac, which generally has a rather bulky package.Searching from alternatives, I found the Snubberless, logic level triac, like ST T1610:https://www.st.com/content/ccc/resource/technical/document/datasheet/67/06/bc/c9/35/8e/4f/ea/CD00002265.pdf/files/CD00002265.pdf/jcr:content/translations/en.CD00002265.pdfThis component seems the best choice for me, because is also suitable for inductive loads (motors) and fast switching PWM modulation.In the Figure 11 (page 12) of the following ST Application Notes (AN439), only a resistor is used from driving the triac, directly from the microcontroller. The low level triac (T1610) requires only a 10mA gate current, so even a microcontroller output can deliver it. There is no isolation, obviously, but I can accept this compromise.AN439 - Logic level and Snubberless TRIACshttps://www.st.com/content/ccc/resource/technical/document/application_note/ca/ef/9d/1e/4a/9f/47/69/CD00003865.pdf/files/CD00003865.pdf/jcr:content/translations/en.CD00003865.pdfHowever, I have a doubt. In the Figure 11, the scheme has the Vcc (+5V) in common with AC line. In my design I'm using an LNK306 with GND in common with AC neutral (or line). Anyone knows if this triac is usable with similar design, but with common GND? I found that this triac (T1610) works only in 3Q (3 quadrant) mode, not in 4Q. I don't know very well the operation theory of triacs, but I found this diagram for triac quadrants:https://apollo.neocities.org/electromotiveforces/quadrants.gifIf I undestood this theory, if I use a digital input to gate, with common GND, the input signal will be positive (+5V or 0V), so the triac should work on Q1 and Q4. If I understood correctly, I cannot use this type of triac with common GND (positive) digital input, because it can't works on Q4, right?For greater clarity, I attach also the scheme of my LNK306 power stage.
TRIAC switching using MOC driver issue with PIC - Page 1
Forum section: electronics / projects

author: VEGETA
author_rank: Super Contributor
timestamp: March 09, 2013, 12:03:17 pm
content: Hi all..schematic in my attachments.I want to design an automatic transfer switch that switches between 2 AC sources. I used MOC driver and a triac for each source.now, the 2 sources must be connected to the same load... but when I run the simulation in Proteus, I have a voltage signal at the load between the value of the 2 sources... which means they are not connected/disconnected properly... maybe the 2 of them are fired together though software don't do that.in my attached schematic I used a clock (one clock is active, the other is not) for firing the 2 of them and it works nicely!!! but when I connect the PIC16F877A and run the code.... that problem happens.so, I figured that I should put the code too.Code:if ( adc1 < adc_rms_min ) { // if source_1 is not active:if ( adc2 >= adc_rms_min ) { // if source_2 is active:source_1 = 0; // deactivate source_1delay_ms(10); // wait 5mssource_2 = 1; // activate source_2source_1_on = 0; // source_1_on LED is OFFsource_2_on = 1; // source_2_on LED is ONno_active_source = 0; // no_active_source LED is OFF}else {source_1 = 0; // source_1 offsource_2 = 0; // source_2 offno_active_source = 1; // no_active_source LED is ONsource_1_on = 0; // source_1_on LED is OFFsource_2_on = 0; // source_2_on LED is OFF}}if ( adc1 >= adc_rms_min ) { // if source_1 is active:source_2 = 0; // source_2 offdelay_ms(10); // wait 5mssource_1 = 1; // source_1 onno_active_source = 0; // no_active_source LED is OFFsource_1_on = 1; // source_1_on LED is ONsource_2_on = 0; // source_2_on LED is OFF}this is the part needed to understand what I want... as you see adc1 and adc2 are for measuring sources' voltage to decide which one to enable... if it's adc above a certain level, connect it.source1 is the primary one so if it's voltage is good it will be connect even if source2 was active, and here it will disconnect source2 then activate source1.so, what wrong thing does this kinda code do?!in the case of using clocks... I used a 1Hz clock for each source, clock1 is low-to-high and clock2 is high-to-low... so each source is active for 0.5s AND it worked perfectly!!! no problems in zero-crossing thing (because the MOC supports it).that means the code have something, right?looking forward to your answers.thanks

author: micro_freak
author_rank: Contributor
timestamp: March 15, 2013, 01:36:22 am
content: triacs will stay latched on until the source crosses zero. maybe you can try to augment the delay from 5 ms to 16ms (60 Hz) to make sure.Give it a try.regards.

author: David_AVD
author_rank: Super Contributor
timestamp: March 15, 2013, 02:55:58 am
content: Are the two sources of AC even the same phase?
Triacs control board - Is this circuit correct? - Page 1
Forum section: electronics / projects

author: atferrari
author_rank: Frequent Contributor
timestamp: October 15, 2014, 03:02:39 pm
content: Triacs control boardFrom an old issue of Elektor, every time I try to understand this circuit which seems to be drawn in a somewhat weird way, I get confused.Could anyone with experience in AC control tell me if it is OK?I will appreciate that.

author: mij59
author_rank: Frequent Contributor
timestamp: October 15, 2014, 03:57:47 pm
content: Hi,The circuit works, to understand what's going on take a look at thishttp://en.wikipedia.org/wiki/TRIAC.The triac is controlled using quadrant 2 and 3.When the opto coupler is turned of, T1 will conduct, and there can flow no gate current OUT of Tri1.Note that the positive terminal is D.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 15, 2014, 04:10:00 pm
content: It's OK.More specifically:For whatever reason, they decided to draw it "upside down". This was common back in the days when electron current flow and PNP transistors reigned, but rare and ugly by today's standards.If you can imagine everything upside down and negated, it works thusly:A, C are like VCC = -8V, and B, D are like GND. All the transistors are common emitter, and they either allow a current (about 7-8mA DC) out of the TRIAC gate, or shunt it to ground, keeping it off.The optoisolators are opposite polarity (NPN), but this doesn't matter much because they're really just being used as switches, too. Namely, the 22k pull-up resistors are keeping the transistor bases forward-biased, so they sit at -0.7V, unless the respective opto turns on, shunting it to ground, turning off the transistor and turning on the TRIAC.The TIC206D says +/-5mA gate current for quadrants 1-3, and 10mA for quadrant 4. This circuit is using quadrants 2 and 3, so the ~7mA bias should be sufficient, at least for casual line switching applications (and probably still fine anyway, for zero-crossing or phase control applications, up to 100-200Hz).Note that a TRIAC is like a BJT, in that positive input current (G-MT1 looks like a diode or Vbe junction) allows positive output current, but it also allows negative output current: when forward biased, the whole damn thing kind of turns into a mushy pile of conductive silicon, and doesn't stop until you let go from all sides (gate AND load current at zero for >> 10us). The gate looks like parallel back-to-back diodes, so it can be "forward" biased witheitherpolarity: it just so happens, one combination (positive gate, negative load -- 4th quadrant) doesn't work so well, and requires a little bit more drive to ensure conduction.Tim

author: eneuro
author_rank: Super Contributor
timestamp: October 15, 2014, 11:22:56 pm
content: Sometimes it is better make own 25Atriacusing two thyristors in parallelHere before final assembly-5mm width tracks covered with added soldered double copper wires 1.7mm in diameter each, so more than 4mm2 of copper per trackAdditionally I use AC mosfets switch to triger this thing with galvanic isolated mosfets gate driver
Triangle waves? - Page 1
Forum section: electronics / projects

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 13, 2013, 02:53:03 pm
content: Hello my LM358 arrived today and i saw many tutorials about it and i have made a reasearch about it too ... but i was trying to create a triangle wave with it with no succes ...My setuppin 4 gndpin 8 VCC(5v)pin 3 3.3vpin 2 square wave with arduinopin 1 -- o led o--- gnda capacitor from Vout to pin 2and a 20k resistor from pin 2 to my square wave.I cant find the mistake ... it should work like a charm...Please help

author: nuhamind2
author_rank: Regular Contributor
timestamp: May 13, 2013, 03:20:30 pm
content: My guess is your capacitor saturated

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 13, 2013, 05:30:35 pm
content: Quote from: nuhamind2 on May 13, 2013, 03:20:30 pmThanks now the led is on but i cant see any effect.... it may be the frequency of the arduino signal!!!And no that was not the problem....

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 13, 2013, 05:38:56 pm
content: Thats was the poblem... i am so dump when i moved the arduino a bit something must have moved and the circuit is working like a charm!!!

author: ivan747
author_rank: Super Contributor
timestamp: May 15, 2013, 01:11:18 am
content: Poor breadboard connections... They are a pain in the ass. Always ensure the wires you use hold tight into the breadboard or connector you are using.
Triax connectors - too damn expensive. Are there cheaper sources? - Page 1
Forum section: electronics / projects

author: Cerebus
author_rank: Super Contributor
timestamp: April 14, 2017, 01:35:41 am
content: This is really one for the Volt-nut crowd but I'm asking here in hopes of a wider audience and therefore a better chance of getting the answer I want to hear.For those not in the know, triaxial cable is often used for low level DC measurements where a shielded cable is needed but where the capacitance of standard coaxial cable is unacceptable. If you use triaxial cable you can drive a guard voltage onto the intermediate shield that mirrors your measurement voltage - thus cancelling out the cable capacitance from the point of view of the measurement conductor while still keeping it all shielded by the outer shield.Anyways, Triax connectors are ******* expensive. Sure, they're less of a commodity item than BNCs but manufacturing wise they can't cost that much more to manufacture than the humble BNC does.We're talking here about the ones that look just like a BNC except that they've got the inner shield contact and three bayonet lugs instead of two - know variously as TRB, MIL-C-49142, TXA and probably a bunch of other names as well. I've seen prices for single connectors well over the £100 GBP mark and the cheapest that I've found so far is around £18 GBP for a bulkhead mounting and £22 for cable mounting. Even with the cheapest I've seen so far that adds up to around £100 for cabling for a single signal (four connectors and a length of cable) and many test setups need at least four (force hi, force lo, sense hi and sense lo.I know there are alternatives that would do the basic job (possibly with a little bodging) and are cheaper such as Twinax connectors, and I believe there are a range of aeronautical triaxial connectors. I would however like to stick with the metrology standard if I possibly can for interoperability with standard equipment.So, does anyone have a source of more economically priced standard Triax (TRB, MIL-C-49142, TXA) connectors than I've managed to find to date?
Trick APC UPS - Page 1
Forum section: electronics / projects

author: boelle
author_rank: Newbie
timestamp: October 07, 2024, 04:19:33 pm
content: basicly i want to trick an apc ups so i can use it as a kind of home battery controllerso i need to able to control when the battery is charged and when the battery is used to drive things, for fun and giggles lets say a fridgeso electricity is cheap during the night and most expensive during the afternoon and eveningmy thought was to expand the battery capacity so i could run without mains for 18 hours at 100W load, and then charge them during the remaing 6 hoursideal i want mains to be connected at all times and only have the alarm go off if mains to the house goes away, and then simply control/tricking the UPSi found one schematic and still eyeballing it for ways to hack it without the ups know that something is offpointers and constructive critism welcome

author: coromonadalix
author_rank: Super Contributor
timestamp: October 07, 2024, 04:33:38 pm
content: normally many smps have monitoring / supervisor ic's, you need to hack them / reprogram them .... but mostly you need code ...because if you have say 2 batteries for a 24vdc system inside, the ups know how to calculate power, remaining time etc ...putting many in parallel will change the calculations ...if it was doable we should have already heard about it ... sorry .. if it was already done, never heard about it

author: boelle
author_rank: Newbie
timestamp: October 07, 2024, 08:08:12 pm
content: yeah, this is why i'm askingthe calculated runtime does not matter to me as i would do a test to confirm the run time is enoughbut yeah, it would require some hacking, i think i will just put a relay in front of the mains input and do a hack to disable the beeper, that i can figure out at leastof course an inverter and batteries could do the same thing, but these APC ups's come up second hand all the time and for far cheaper than inverter+battery+charger would cost

author: CaptDon
author_rank: Super Contributor
timestamp: October 07, 2024, 11:40:29 pm
content: Even though night time electricity is cheaper, do you really save anything with the inefficiency of the battery charge cycle plus the inefficiency of the inverter itself while converting battery energy to mains equivalent energy? Sounds like an over engineered net loss to me.

author: boelle
author_rank: Newbie
timestamp: October 08, 2024, 06:08:22 am
content: well the savings between the high peak during late afternoon / evening and night is arround 0.50 dkk each kwh, and arround 0.12 DKK the rest of the timeof course its not 100% effective since we have conversion involved and i knew that from the start, but you save a little, the batteries will be replaced with lifepo4 cells so they last longer, but yes higher up front costthe goal is to save in the long run, and as inflation goes these days every little bit counts
Tricking garage doors - Page 1
Forum section: electronics / projects

author: sancho_sk
author_rank: Newbie
timestamp: January 21, 2018, 10:22:29 pm
content: I have a small project on my mind.I park my car in a local garage. The doors take quite some time to open and I have to wait in front of it, which bothers me.I'd like to "fool" the sensor of the doors to make it start opening the gate as soon as I start my engine.The problem is, my car (and a possible 230V power source) is parked good 10m from the door.I believe the door opens based on PIR sensor - even if I walk in front of if, it works, so it does not need to be something as big as car.Of course, I cannot make any direct modification of the electrical wiring or devices owned by the landlord...I was thinking about triggering the sensor somehow - black body radiator style. My initial thought was to use some heat source to project heat onto the sensor path, but I am too far and out of defecting angle to do so.Does anybody have any ideas how to achieve my goal?Any tips are welcome.