I like the idea @b_force posted in #47, current sensing relay could be the solution!
Here is another example of current sensing switch.
How would you get it to latch in the off position? Otherwise a buzzer.
Another out of the box thought, how about tricking a GFI circuit breaker into opening by deliberately leaking some of the load current into its ground terminal? I assume they're pretty quick...
Power to the load should be cut off by a latching relay, I think it is doable. Some even featured adjustable delay timer.
The point I was making that with matched parts in the driver and LED, there is less chance of error in matching the items.
The only culprit then is voltage fluctuation, or spikes, and in cheaper computer SMPS I have seen links where the NTC should have been, as a cost cutting measure.
So the solution is to use a spike buster, as the drivers are usually tolerant of minor mains fluctiations.
And the lamps are about $1 or so, might as well keep a few around as spares for when needed.
They are sold in grocery stores now...and I have seen people using them in parallel where a larger LED 'tubelight' would be needed...cheaper and more reliable than the 'tubelight'.
The only culprit then is voltage fluctuation, or spikes, and in cheaper computer SMPS I have seen links where the NTC should have been, as a cost cutting measure.
So the solution is to use a spike buster, as the drivers are usually tolerant of minor mains fluctiations.
And the lamps are about $1 or so, might as well keep a few around as spares for when needed.
They are sold in grocery stores now...and I have seen people using them in parallel where a larger LED 'tubelight' would be needed...cheaper and more reliable than the 'tubelight'.
I think you mean it needs hysteresis?
I have no idea of any of these simple current sensor have that to be honest.
I personally would use a sample-hold circuit instead.
If there is any interest, I can make some kind of PCB specifically for these kind of things.
Although, in that case I might as well just use a microcontroller to also monitor the power and such. 🙂
The most difficult part is to make it universal for different kinds of power requirements.
Most tube amplifiers and radios don't go much higher than say 50-100W, while solid state power amplifiers often go up to 500W.
Currently designing a simple cheap (under $5) "electronic fuse" for my Guitar amps.
SICK of getting amps for service with an over rated fuse in the holder.
I need something that works but can NOT be messed with by user.
It must also cost not much more than a plain fuse and holder.
Those electronic switches shown above are beautiful but way too expensive to routinely add one to every amp, they are perfect for bench use though.
I think I can solve the latching aspect by using an SCR so I can use a cheap standard relay instead of a custom latching one.
Sounds dangerous to me 🙁
I would straight copy the relay activating section but trigger it with a current sensing resistor, say 0.1 ohm in series with Mains or whatever value is needed.
0.7V peak are enough to trigger an SCR, a few millisecond delay or some integration must be added so as to avoid nuisance triggering.
Some delay similar to what T rated fuses offer.
Tricky without a relay.
For on my bench I just use a automatic circuit breaker for now, they also come in very compact sizes.
But that is obviously not a solution in your case.
There are PCB variants, but the nice and compact ones aren't cheap; (still about 8 buck in quantities of around 100)
These are only 2-3 bucks or so, but a bit bulky; (about 50mm long)
Just mounting a little fuse holder inside with the correct fuse is probably MUCH easier and cheaper.
A second fuse inside the chassis is often a solution. You can even get self resetting ones!
https://www.belfuse.com/resources/datasheets/circuitprotection/ds-cp-0zre-series.pdf
https://www.belfuse.com/resources/datasheets/circuitprotection/ds-cp-0zre-series.pdf
Domestic blender type circuit breakers / bimetal breakers may suit that purpose.
A current sensor controlling a triac to main supply with reset function, using a current transformer to sense loads, is an expensive solution and will take time to design.
It will temporarily cut off mains till sense prevails...
A current sensor controlling a triac to main supply with reset function, using a current transformer to sense loads, is an expensive solution and will take time to design.
It will temporarily cut off mains till sense prevails...
I said:
so I can use a cheap standard relay
🙂
Interesting.
Can you post links ?
Although we have a new crazy President since yesterday who started by devaluating Argentine Peso (so doubling USD cost) by 200% , on top of the last Economy Minister , also (losing) Presidential Candidate, who had previously applied 100% (patriotic) + 55% (presumed earnings) + 30% (Quatar, not kidding) taxes so $5 cheesy part ends up costing $39
Add postage to that and you'll understand why I make everything in my small Factory, from transformers to speakers to PCBs to chassis plus handles, rubber feet, corner protectors, knobs, etc.
Oh well, "what doesn't kill you makes you stronger"
Just for a masochist reference: USD price in Argentina.
The blue line is the "official" value (which today got devalued 2:1); the white line is what I must pay. Also jumped 2:1 6 hours ago.
The quickest way is just to go to fuse and breaker section at Mouser or Digikey.
Yeah, sorry to hear about your unfortunate situation. All the best!
I am about to reveal the great secret to obtain an incandescent light bulb. So please do not read on if you are faint of heart or liable to blab to eco-terrorists!
Oven lamps are incandescent as it should be obvious Led light bulbs are not really suitable to use at high temperatures. They are typically 40 watts. So one or two may be used in parallel for most electronic tests.
I also like to have a high wattage lamp available for testing some of the larger power amplifiers. I have both 200 watt and 500 watt incandescent bulbs. They are sold for photography! Although Led types are creeping in. https://www.bulbamerica.com/collections/photography-bulbs
Oven lamps are incandescent as it should be obvious Led light bulbs are not really suitable to use at high temperatures. They are typically 40 watts. So one or two may be used in parallel for most electronic tests.
I also like to have a high wattage lamp available for testing some of the larger power amplifiers. I have both 200 watt and 500 watt incandescent bulbs. They are sold for photography! Although Led types are creeping in. https://www.bulbamerica.com/collections/photography-bulbs
At one time I saw that they were using leds for traffic lights in my locale. seems that they stopped using them and went back to incandescent lamps, so they are another source to consider.
The issue with LED bulbs and photography -- some of the LED bulbs flicker at a rate which, for digital cameras, creates a "light standing wave", i.e. mysterious streaks. The shutter speed of a film-camera is slow enough to integrate the flickering. I don't have this issue with my Fuji XE2 camera, but others have reported issues.
I just ordered a bunch of 150W industrial incandescents for the laboratory. Working on some ham radio receivers.
"Industrial incandescents" ... "Medical marijuana" ... the World is chock full of restrictive Laws ... and corresponding bypasses/loopholes/you-name-it. 😉
During Prohibition, Vermouth was exempted because it could be considered "Medicinal upset stomach Tonic" ... which by the way is true, because of the herbal extracts it contains.
Oh well 🙂
During Prohibition, Vermouth was exempted because it could be considered "Medicinal upset stomach Tonic" ... which by the way is true, because of the herbal extracts it contains.
Oh well 🙂
