Home
Help
Search
Login
Register1
Repair / Re: Mig welder wire feeder controller board not working
« Last post by xavier60 on Today at 02:41:50 am »Where was the 24VAC measured? There appears to be a PCB mounted control transformers supplying multiple regulators.
Recent Posts
2
Repair / Re: Mig welder wire feeder controller board not working
« Last post by floobydust on Today at 02:33:55 am »Quick eyeball check - the relay has one set of contacts that look destroyed. The power transistor bottom left looks like it's run hot a lot, poor heat transfer to the heatsink.
A real mix of brands of electrolytic capacitors, I would replace the cheap ones. 1999 was a while ago.
A real mix of brands of electrolytic capacitors, I would replace the cheap ones. 1999 was a while ago.
3
Thermal Imaging / Re: Looking for a new lens
« Last post by Hazel on Today at 02:28:40 am »Hi,Did you find the lens you needed?
4
Beginners / Re: Question about use of Differential using scope USB port
« Last post by RJSV on Today at 02:26:31 am » It's a good question, when caring about safety, but maybe too general. Perhaps focus on one thing and associated question, rather than a vague, general 'things that were discussed'.
Grounding ties, and related safety should be specific to one instance, (and I don't claim to have that comprehensive).
Certainly a 'one handed' rule should specify maybe a rubber mat / shoes also, while explaining the ground paths that are to be avoided...Metal shop chair ? Ditto, as something like metal chair, with rubber feet, and in a mat, could be, cautiously, tolerated.
See how detailed and specific that was ?
But I'm not expert. Perhaps there is (or should be) a National Electrical Code unit, in D.C. that could answer / respond to the subject on Oscilloscope grounds and related recommended practice(s).
Wouldn't be surprised, if (any) agency would be 20 years behind the times, but that's normal in large agencies.
Grounding ties, and related safety should be specific to one instance, (and I don't claim to have that comprehensive).
Certainly a 'one handed' rule should specify maybe a rubber mat / shoes also, while explaining the ground paths that are to be avoided...Metal shop chair ? Ditto, as something like metal chair, with rubber feet, and in a mat, could be, cautiously, tolerated.
See how detailed and specific that was ?
But I'm not expert. Perhaps there is (or should be) a National Electrical Code unit, in D.C. that could answer / respond to the subject on Oscilloscope grounds and related recommended practice(s).
Wouldn't be surprised, if (any) agency would be 20 years behind the times, but that's normal in large agencies.
5
Microcontrollers / Re: SD Card reliability in SPI mode
« Last post by betocool on Today at 02:21:30 am »Thanks for all your answers.
Looks like I can address a few things.
For this project, space is a premium, so additional memory is out of the question. I might consider a NAND flash but I've been down that road before in the past with less than stellar results too. That also requires major hardware changes and yes, time is also a premium!
The SD Cards I'm using, or tested really, are Verbatim brand, they are the most common here in OZ, 32GB. I tried the "Extreme" with a gray stripe, that seems to fare worst. I also tried the one with a golden stripe, that one performs better, but we've still had issues. I will later try out one of the Endurance series (I don't recall the name 100%, don't have the hardware with me) which are completely white, we'll see how that goes.
I will try synching less often, that might help, and I will also wait until there is really no data going on for a few hundreds of ms before turning the card off. As usual all these things take some time to implement but much longer time to test. We'll see.
I appreciate all your comments.
Cheers,
Alberto
Looks like I can address a few things.
For this project, space is a premium, so additional memory is out of the question. I might consider a NAND flash but I've been down that road before in the past with less than stellar results too. That also requires major hardware changes and yes, time is also a premium!
The SD Cards I'm using, or tested really, are Verbatim brand, they are the most common here in OZ, 32GB. I tried the "Extreme" with a gray stripe, that seems to fare worst. I also tried the one with a golden stripe, that one performs better, but we've still had issues. I will later try out one of the Endurance series (I don't recall the name 100%, don't have the hardware with me) which are completely white, we'll see how that goes.
I will try synching less often, that might help, and I will also wait until there is really no data going on for a few hundreds of ms before turning the card off. As usual all these things take some time to implement but much longer time to test. We'll see.
I appreciate all your comments.
Cheers,
Alberto
6
RF, Microwave, Ham Radio / Re: High bandwidth FM signal generation
« Last post by David Hess on Today at 02:21:07 am »Incidentally, "triangulation" as a DF or interference-hunting methodology is, in my experience, both very overrated and very misunderstood. Unless you are in a more or less reflection (multipath) free environment, it's very difficult to get good bearings: calculating the interception of those bearings is trivial, but junk bearings yield junk results.
It becomes more difficult at higher frequencies where reflections become stronger. Roanoke style Doppler direction finding systems have a lot more trouble than systems which rely on a beam antenna, but the sidelobes on beam antennas create their own problems. Even in challenging environments, I had excellent results with beam antennas designed to have a minimum of sidelobes, at which point it was possible to see multipath from things like trees which otherwise was concealed by stronger sources. With a really good antenna, one can "see" the terrain from its reflections. Once I had a good enough directional antenna, I could track flights into and out of LAX from their reflections as a form of poor man's bistatic radar.
Quote
Since interference / jamming happens around (or at least is important around) people, this means most practical DF'ing is being done in urban and suburban environments where multipath can be an issue.
That was definitely my experience. Large buildings with flat surfaces make for a challenging environment.
Quote
For cellular network operators, they know from the base station stats (RSSI, e.g.) which sector or sectors are being affected, and in most cases you can simply drive (or walk) the sector until you get close and have to hunt on foot (where triangulation is completely useless).
Triangulation is not always necessary. Once a direct path at close range is available, a rise in signal strength of 6dB indicates that the distance has halved, making an estimate of distance to the target possible. This of course depends on having a beam antenna with low sidelobes to reject multipath interference.
The 6dB rule applies equally well to reflections, so at close range it may be necessary to back off and find a higher location to try and lock onto a direct path signal.
Quote
Just wonder is it possible to use some kind of synchronized array of transmitters distributed all around the base stations and transmitted signals in that way so their interference signal at base station location gives false position of the transmitter or just spamming it with a bunch of virtual transmitter positions to make it hard to find which one is real? Are such kind of jammers are used in practice?
There are a lot of "creative" approaches to jamming, but high-end direction finding systems (like the ones we make) can usually still DF people trying to use "creative" techniques. Generally speaking, for a jammer to be effective it has to be (a) loud, (b) wide, and (c) on, and all three of those things make jammers relatively easy to DF, regardless of how they are implemented. A weak signal with a low duty cycle that's only a few kHz wide is harder to DF, but it's also not an effective jammer.
I tried something once on one of our amateur band transmitter hunts which was somewhat effective. We hunted standard 2 meter FM signals, but knowing how signal strength and noise meters responded, I modulated the amplitude with low frequency noise through an exponential circuit to create a linear response on various signal strength meters. This made it more difficult for hunters who relied on signal strength to gain a bearing, but had no effect on Doppler direction finders of course.
7
Beginners / Re: Is this 220v capable board? (Dewalt DCB095)
« Last post by Taras Motruk on Today at 02:20:59 am »Just got registered on this forum to confirm, that DeWalt Charger DCB095 purchased in US and labelled as supporting 120V AC 60 Hz input voltage only was tested on 230VAC 60Hz and found working perfectly fine.
The board in my charger is built exactly same way as on photos from topic starter - input rectifier filter electrolytic capacitor is mounted with voltage label down thus no chance to read what is rated voltage, but thanks to info posted in this forum topic I got confidence that the charger is 230VAC ready. That is really great because I was already thinking to by voltage converter for this charger to use it on 230VAC network.
By the way, gyroscopic cordless screwdriver DeWalt DCF680 is amazing tool, I couldn't fine anything similar from another brand - thank you DeWalt!
The board in my charger is built exactly same way as on photos from topic starter - input rectifier filter electrolytic capacitor is mounted with voltage label down thus no chance to read what is rated voltage, but thanks to info posted in this forum topic I got confidence that the charger is 230VAC ready. That is really great because I was already thinking to by voltage converter for this charger to use it on 230VAC network.
By the way, gyroscopic cordless screwdriver DeWalt DCF680 is amazing tool, I couldn't fine anything similar from another brand - thank you DeWalt!
8
Repair / Mig welder wire feeder controller board not working
« Last post by .RC. on Today at 02:17:53 am »So I decided to turn on my older transformer mig welder that has sat idle for a couple of years, it was working fine when last switched off. The machine powers up but the wire feeder is dead. I have wriggled wires and measured a few voltages and the board is getting power but nothing happens when I pull the welding trigger.
The board gets fed 24V AC power, and I have gone so far as measuring 34V on the board after the bridge rectifier. The board does multiple things. When you pull the trigger on the welding handpiece, it should send voltage to a gas solenoid to turn the gas on. It should send voltage to the wire feeder motor to feed motor, which I suspect is via PWM, it also send voltage to turn on a main contactor for the welding transformer.
The board has inputs of a potentiometer for the wire speed, a burnback potentiometer that means after the trigger is released the wire feed is cut the welder still welds for a fraction of a second more. and a toggle switch to control what happens when you pull the trigger on the torch, either a simple on/off, press once for on and press again for off.
The board seems in good condition and there are no obvious faults, all through hole, double sided tracks.
I am not sure where to start trouble shooting due to my inexperience. I can solder desolder through hole stuff OK. Have multimeter, DC power supply and oscilloscope on hand.
Since nothing works I would suspect the power supply side of the board. I am sure it is repairable especially as I assume it is all analogue.
The board gets fed 24V AC power, and I have gone so far as measuring 34V on the board after the bridge rectifier. The board does multiple things. When you pull the trigger on the welding handpiece, it should send voltage to a gas solenoid to turn the gas on. It should send voltage to the wire feeder motor to feed motor, which I suspect is via PWM, it also send voltage to turn on a main contactor for the welding transformer.
The board has inputs of a potentiometer for the wire speed, a burnback potentiometer that means after the trigger is released the wire feed is cut the welder still welds for a fraction of a second more. and a toggle switch to control what happens when you pull the trigger on the torch, either a simple on/off, press once for on and press again for off.
The board seems in good condition and there are no obvious faults, all through hole, double sided tracks.
I am not sure where to start trouble shooting due to my inexperience. I can solder desolder through hole stuff OK. Have multimeter, DC power supply and oscilloscope on hand.
Since nothing works I would suspect the power supply side of the board. I am sure it is repairable especially as I assume it is all analogue.
9
General Technical Chat / Re: Bad Electronics Jokes
« Last post by MK14 on Today at 02:12:36 am »Q: Does anyone want a pile of dead batteries, I've accumulated?
A: If you do, you can have them, free of charge
A: If you do, you can have them, free of charge
10
FPGA / Re: Analog video output with FPGA ?
« Last post by SiliconWizard on Today at 02:08:15 am »I'd recommend one of those ADV chips BrianHG mentioned. Yes, overkill but easy to use and good.
For your use case though, if color accuracy is not really a concern and given the low bandwidth, you could just go for R-2R ladders. Apart from color accuracy, I don't see why this would cause any problem especially at those low resolutions. For better results though, I would recommend going via external buffers rather than straight from the FPGA IOs, at which point, the integrated DACs will end up only a tad more expensive.
For your use case though, if color accuracy is not really a concern and given the low bandwidth, you could just go for R-2R ladders. Apart from color accuracy, I don't see why this would cause any problem especially at those low resolutions. For better results though, I would recommend going via external buffers rather than straight from the FPGA IOs, at which point, the integrated DACs will end up only a tad more expensive.