Just when I was happy that the casing for a new 24V 3A PSU is almost slotless. 100% airtight is not OK but having little heat or leading that little heat to the casing itself is elegant designing IMHO.
The opposite: devices that generate useless excess heat so with many slots so dog hairs (yuck), dust, insects, dried up spilled fluids and other dirt and corrosion on parts. The icing on the cake is a stupid fan with squeeling bearings.
The opposite: devices that generate useless excess heat so with many slots so dog hairs (yuck), dust, insects, dried up spilled fluids and other dirt and corrosion on parts. The icing on the cake is a stupid fan with squeeling bearings.
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I own a coffee machine with a heater element, a heat sensor (disconnecting power) and an on/off switch.
In most cases that will suffice.
A microcontroller is added to make the power led flashing to notify the user coffee is ready to serve.
In the meanwhile, the glass coffee pot cannot withstand the heat and cracks within a month.
The next upgraded version will come with wireless control and a 'coffee-app' (paid subscription with further benefits).
This seems to be a useful contribution in the context, but my dictionary does not know what "bich-and-groan" is ..
I would like to find a laptop PSU with vents.
Most of them run hot and You'll have to crack the case to replace the broken cable or connector.
I drilled holes in my cordless phone linear wall wart to add ventilation. Ran cool after that.
You can try that for a laptop brick.
Some street light drivers are encapsulated for weather protection, bear that in mind.
You can try that for a laptop brick.
Some street light drivers are encapsulated for weather protection, bear that in mind.
I quite agree J-P.
Back in spring 2019 I replaced the under-cabinet lighting in my kitchen with Luxeon mid-power LED strips, 4 strips with a total draw of 400mA at 34V, all 4 strips put out a total of around 4300 Lumens at full brightness.
That's about 300 watts worth of light, plenty for the kitchen counter lighting.
But I wanted a simple noiseless supply that was adjustable/dimmable and compact, tucked inside one of the wall cabinets, with an easily accessable power switch and knob through the bottom of one cabinet for control.
I chose a Hammond diecast aluminum box, containing a low-profile transformer, my own dimming supply design, and having ultimate reliability.
Naturally, It's got my trademark "over-built" design, I just want to make something once, and not have to fool around with it again in my lifetime.
The LM317 regulator and power transistor are on a heatsink and that is bolted inside to the case, to add to the heat-dissipation properties, although it never gets beyond slightly warm.
And it works beautifully the past 4 years!
I can dim the lighting to a 'night light' level, or full brightness, for cleaning the counters, doing dishes, or preparing food.
No 'design errors' here, I can assure you!
And the cost of all parts was very reasonable too.
I restore receivers and ham radio equipment. The most frequent failure I have seen are badly designed grounds...as a matter of fact I consulted with Anatech on a Yamaha which had gone wonky -- bad ground connection which punked out after a few decades.
I don't think the folks at Heathkit purposefully designed the ground connection inside the LMO in their receivers to fail -- but these in the SB-line are getting on to 55 years of age!
I don't think the folks at Heathkit purposefully designed the ground connection inside the LMO in their receivers to fail -- but these in the SB-line are getting on to 55 years of age!
@wiseoldtech: Nice! Next time you could consider using Schottky diodes, a way lower output voltage transformer like 22V and LT1085 or LT1086 which have 1.3V drop and no pass transistor and 5W resistor needed. Again a few Watts of heat saved. Just thinking out loud.
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Some Vincent Audio power amplifier utilize a relay NC contact shorts its input to ground when the amp is off.
Is it an error or bad design decision?
Is it an error or bad design decision?
Could be neither of both. Maybe the input has a high DC offset voltage when switched off which may damage sources. It is there with a reason. Maybe the light bulb there needs a higher DC voltage that shows up at the inputs at power down?
IMO, it is bad for the source connected to it, I think instead of shorted the source output, it's better to disconnect the input jack.
I had an Arcam Alpha stereo amp once which was repaired 3 times under warranty due to a design fault in the psu.
Even when it was working it was the worst sounding amp I've ever owned.
No it can be life saving for the source connected to it and if my DC hypothesis is right it will prevent you from getting shocks too when you desire to change RCA cables. That source has probably muting relays shorting outputs to GND itself too which essentially does the same. Apparently the designers wanted no risk at all. No source will die from double muting, sources will die without muting. No source should have issues with shorted outputs as that is the only way to guarantee complete silence and 0.000000V DC. Just suppose and/or measure that device. If it has let's say 90V DC at the inputs at power down you'll know why they muted the inputs. Many beautiful semiconductor devices have been killed by tubes and this should stop right now says the activist in me!!!
Besides that: life's too short for enduring plopping/farting devices for years in a row although some seem to experience that as quality 🙂
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The "new" fashion is to use extremely thin inflexible wires with a single strand. This makes repair a pain, as wires break very easily and make inspection and testing, a pain if not an impossibility.
In the past A lot of preamps used to short the unselected inputs
to ground. When I rebuilt my HK CIT I ( which shorts unused inputs)
I noticed bleed-thru from the tuner when phono was selected.
The shielded cables from the tuner and phono were run right
next to each other. I replaced all the input shielded cables
with new cables, added a 1K resistor to all line level inputs.
Then I rerouted the phono cables outside of the collection
of input cable wires. No more bleed thru.
Design fault, I think not. If a tube tuner was used, not enough
current would be in the tuner cables to bleed thru the to the
phono cables.
to ground. When I rebuilt my HK CIT I ( which shorts unused inputs)
I noticed bleed-thru from the tuner when phono was selected.
The shielded cables from the tuner and phono were run right
next to each other. I replaced all the input shielded cables
with new cables, added a 1K resistor to all line level inputs.
Then I rerouted the phono cables outside of the collection
of input cable wires. No more bleed thru.
Design fault, I think not. If a tube tuner was used, not enough
current would be in the tuner cables to bleed thru the to the
phono cables.
The problem with the Vincent power amplifier is if you use one preamp connect to two power amplifiers in two rooms via Y connection cable, you always need to power up the Vincent even you're not in that room. Otherwise, no music!
BTW, some preamp has no power switch in front panel ( preferred always ON? ). A design fault?
BTW, some preamp has no power switch in front panel ( preferred always ON? ). A design fault?
Driving two loads in parallel with one switched off can also cause problems when there is no input relay. ESD protection diodes to a switched-off supply and to ground can cause gross distortion. I learned that by connecting a Philips CDR775 CD-recorder to the recording output of a Technics amplifier that has no recording output buffer.
Thanks J-P, but those LED strips need 34.8 volts for full brightness, and are night-light dim at 30 volts.
Each strip contains 2 strings of 12 LEDS in series, both strings are paralleled.
A 22 volt transformer would only give 31 volts DC directly (22 x 1.414 =31).
I mis-quoted my earlier mention of current for those strips. - at full brightness (34.8V) each strip (24LEDS) draws 200mA, for a total of 800mA from the power supply.
The 30 volt Triad transformer is rated at 1.2A, and barely gets warm.
@jean-paul
Yes, J-P, I understand that.
But even a 24VAC can only produce 33 volts DC peak if used directly to the LED strips I use.
And at that 33 volts, they're only at around 80% brightness.
At 30 VDC, they're a dim glow.
My design gives a full bright light at 34.5VDC, just under the Max level of 36.8VDC rating of the strips.
I'm not worried about a few watts or heat, in operation the system draws only 34 watts from the 120VAC plug, gives me 300 equivilent watts of brightness, and the box when touched is barely above room temperature if left on for hours.
So it's like having a dimmable 75 watt bulb above each countertop area in the kitchen.
Yes, J-P, I understand that.
But even a 24VAC can only produce 33 volts DC peak if used directly to the LED strips I use.
And at that 33 volts, they're only at around 80% brightness.
At 30 VDC, they're a dim glow.
My design gives a full bright light at 34.5VDC, just under the Max level of 36.8VDC rating of the strips.
I'm not worried about a few watts or heat, in operation the system draws only 34 watts from the 120VAC plug, gives me 300 equivilent watts of brightness, and the box when touched is barely above room temperature if left on for hours.
So it's like having a dimmable 75 watt bulb above each countertop area in the kitchen.