Power Supply
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Posted by Broderick Crawford ililililil on December 16, 2007, 8:45 pm
Please log in for more thread options supplies any more? What was it for, a monitor? It was in addition to the AC input cord to take AC back out again. | ||||||||||||||||||||||||||||||||||
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Posted by DevilsPGD on December 16, 2007, 10:37 pm
Please log in for more thread options My guess is that not enough people used it to justify the expense and/or waste of space. | ||||||||||||||||||||||||||||||||||
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Posted by Andrew Smallshaw on December 17, 2007, 8:58 am
Please log in for more thread options >
>>Why don't they make that AC ICE power connector on computer power
>>supplies any more? What was it for, a monitor? It was in addition to the >> AC input cord to take AC back out again. >
> My guess is that not enough people used it to justify the expense and/or > waste of space. There are two relevant issues here, both in relation to turning the monitor on and off. The old style AT power supplies cut the monitor's power at the same time as the system. This was easy to do as the power supplies were controlled via a mains rated latching switch - both the computer and the monitor were fed from this switch so both turned on and off at the same time. ATX power supplies don't have this, at least not on the front panel, so switching a mains power supply would mean a seperate relay or DIAC which would be physically big and/or comparatively expensive. The ATX power supplies that do have monitor outlets don't switch it - they permanently feed the monitor regardless of whether the computer is on or off. In addition, slightly before ATX became widespread monitors began shipping with DPMS power signalling as standard. This means that the monitor powers down when no signal is being fed to it. This isn't as good as cutting the power as the monitor is still drawing some power in a standby mode, but it is most of the way there. In short, controlling the monitor's power is both less important and less practical than it used to be. Since that was the main merit of a monitor outlet the outlet is of less significance today. Since it costs money to fit manufacturers frequently don't bother. One final, and fairly unconnected point. The power rating of PSUs has increased steadily over the years. Whereas 10-15 years ago a 250W PSU was pretty much standard, today the standard is probably 550W. That makes everything inside the PSU case bigger and hotter. Since the PSU is of standard dimensions it means that there isn't as much spare space inside as there used to be. If there are space and cooling constraints then space consuming options such as the monitor outlet are going to be obvious targets. -- Andrew Smallshaw andrews@sdf.lonestar.org | ||||||||||||||||||||||||||||||||||
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Posted by Andrew Smallshaw on December 19, 2007, 5:53 am
Please log in for more thread options >
> Perhaps, but consider that some of these same distributors > may want pretty near the same cost for a fan, at least in > the states I've found Digikey/etc want way too much for some > parts I used to buy in volume for under $1 a piece. It happens everywhere, not just in the US. Just don't confuse pricing on surplus components with regular pricing. I have an ITX system in my bedroom that was from bargain components - the case was £9 against the same supplier's current catalogue price of £60 - the PSU alone sells for £22. The motherboard isn't a standard stock item but it set me back £25 vs £139 for its nearest equivlent in the book - again from the same supplier. Someone made a loss along the line there. > a solid state relay, or one built discretely, shouldn't
> generate an excessive amount of heat just to power a > monitor, and tends to be far longer lived than a mechanical > relay, except that we're not talking about something meant > to be on a space probe or have a very large number of > cycles, it will most likely outlive the rest of the PSU > either way. A triac typically has an on resistance of a few hundred milliohms, and even monolithic SSRs usually end with a triac as the current-bearing component. That means a power dissipation in the order of a watt or so tops, maybe twice that in the US with the lower AC voltage. Given that it is in the PSU, and therefore the last thing in the system as far as airflow goes, on reflection I'll agree with you. It is far less heat than the choppers put out. Of course this is all theoretical anyway since nobody actually does it. > ... and some may not know you can't do something like daisey-chain
> one system running through the outlet of another's supply and so > on, till you have several amps going through that relay or whatever. I hadn't thought of that but you're probably right - that is going to be a problem when the outlet isn't switched. Never misunderestimate the stupidity of the end user. Make the pie higher! Make the pie higher! -- Andrew Smallshaw andrews@sdf.lonestar.org | ||||||||||||||||||||||||||||||||||
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Posted by HDRDTD on December 17, 2007, 9:23 am
Please log in for more thread options Yes it's a throwback to long, long ago when IBM PC's and their clones first
came out. Way back then all you have were simple text monochrome monitors (long before vga ) and perhaps some of the early CGA monitors that had a short power cord that just plugged into the AC recepticle on the back of the power supply rather than a long ac cord that would plug into the wall. That way, when you turned on the PC, it also powered up the monitor. > Why don't they make that AC ICE power connector on computer power
> supplies any more? What was it for, a monitor? It was in addition to the > AC input cord to take AC back out again. | ||||||||||||||||||||||||||||||||||
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>supplies any more? What was it for, a monitor? It was in addition to the
> AC input cord to take AC back out again.