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96

I am an EE system designer. I have designed many PC systems (and non PC ones). I do lots of power supply work and have dealt with many HDDs. As always, there is bound to be an exception somewhere. If someone told me to design an exception I certainly could, but here is my take: 30 seconds was always overkill in terms of any digital state. Even very ...


61

The socket (or rather inlet) is most definitely standard, it’s a IEC 60320 C14 inlet. The standard was published in 1970. C6 and C8 are commonly used for laptop power supplies and smaller audio equipment. There are a number of reasons to use this arrangement on computer power supplies, monitors, audio equipment etc., including: using a standard inlet with ...


60

Epoxy offers two advantages -- it is an electrical insulator, and it conducts heat better than air. Transformers and inductors are generally potted with epoxy for this reason. [ref] Perhaps the cause of the high failure rate is that Commodore engineers decided they could use cheaper components to build the power supplies, depending on the epoxy properties to ...


54

The reset button does not affect the power supply at all. It sends a reset signal to the CPU (and probably the bus). Some power supply designs indeed will wear quicker if quickly switched on and off, but this is not typically about still-charged capacitors. Depending on the circuitry, the following things among others could be a concern: Cumulative thermal ...


46

The reason for any higher frequency supply is almost always the same: you get to convert a single input to different voltages for less wasted heat in a smaller volume. Such systems were very common in applications where you have lots of different voltages downstream from the plug. The first small version I'm aware of was the motor-generator sets used for ...


33

Internal power supplies, while not universal, were not unusual at the time. The major considerations were cost, ease of design, and safety (that is, passing safety regulations that already existed in most first-world nations), with thermal considerations factoring in somewhere further down the list. The latter tended to point towards implementing a switch-...


25

I'm not sure that in 1986, the state of the art used 400 Hz as a frequency for timing the signals and the circuits. The 400 Hz is not related to any kind of timing. It's about getting size and losses of transformers down. With increasing frequency, the efficiency of transformation increases, thus producing less waste heat. At the same time sizes of the ...


23

I will start with the last question: The power adapter is a very cheap one. In fact, the voltage without load can raise up to 15-16V. 9V is the nominal supply voltage under the normal load that the Spectrum circuit imposes. Why 9V? It was a "standard" voltage setting at the time (equivalent to six 1.5V batteries), so transformers whose secondary winding ...


23

It's because the C14 connector is rated for higher current (10A, up to 2400W), which means that it must be attached to a thicker and thus more expensive and less flexible cable. The cable can't be rated lower than the connector for safety reasons. The C6 can only supply 2.5A (600W in 240V countries) so can use a thinner, lighter and more flexible cable that ...


22

The Commodore 64 requires a power supply that provides both 9V AC and 5V DC. If you're interested in building your own, the power supply has a male circular 7 pin DIN connector. Pins 1-3 are ground (pin 2 is the 5V ground), pin 4 is either unconnected or +5V, depending on the version, pin 5 is +5V, and pins 6 and 7 are 9VAC. (source)


22

My best guess is that it was (and is) all about getting the computer into a well-defined state. To make the CPU start at the correct address, it needs to get a RESET signal or something equivalent. And in the old days this was often generated by slowly charging a capacitor at power-up, so that RESET stayed low for some time after applying power. And ...


21

Do not use an original Commodore 64 power supply, especially if it has not been tested. They're prone to fail, and when they do, they'll take the C64 with it. But if you do intend on using one of these power supplies, people have developed hardware that go between the Commodore 64 and power supply and can protect the C64 from power supply failure. The ...


21

Electricians some times (or used to) do similar techniques when configuring wiring -- once the wires were in place, they would fill the cavity with a non-conductive resin or epoxy, so that the chance of any movement or shift in the wiring would cause a short or a disconnect is greatly reduced. I've seen this in numerous situations myself, including air ...


20

In general, no. Cartridges from the first few generations were really only breakouts for ROM chips and thus were mostly a collection of address and data lines with a +5V and GND at minimum and perhaps a few others. In the case of the Intellivision, it also had SYNC, serial lines and a video passthrough (to support IntelliVoice, Atari 2600 module, etc.). The ...


17

World Of Spectrum says: Input: 240V AC, 50Hz Output: 9V DC, 1.4A Centre Polarity: -ve (inner diameter is 2.5mm)


17

This is done to stop HF noise from spreading through the VCC rail. The VIC and the 8701 clock generator (U31) run at much higher speeds than the rest of the C-64, and thereby generate more HF noise than the other components. My understanding is that it's called "CAN +5V" because it supplies the components in the shielded metal "can" on board. [1] Note that ...


16

All the other answers talk about delaying switching back on to prevent possible damage/wear of the power-supply (which I fully agree with). The other reason for a delay that was "common knowledge" way back when was to prevent damage to hard disks. In normal use, the heads of a hard-disk are incredibly close to the platters, and it is partly the spinning of ...


15

Any real attempt to use the momentum of the spinning disk to generate power would cause the disk to come to a halt very quickly. In essence, this is the principle behing regenerative braking of electric vehicles. Otherwise, you would have a perpetual motion machine. However, there certainly were computers that used the momentum of a disk that was spinning ...


15

(This is about motivation (the why) of defining and adding a standard socket to devices and ment as an addition to Stephen Kitt's great explanation of the technical side - at some point a merge might be useful) Most home electrical appliances use a fixed power cord and have a on/off switch near the front. That's due the fact that for appliances sold in ...


14

You can find a list of capacitors and other analog board components here: https://docs.google.com/spreadsheets/d/132RwzC8HM5ask-BdY_31txErOCwJDSkz099GY2XLpE0/edit?hl=en&hl=en#gid=0 This list is maintained by James Wages. The analog boards for the 128k, 512k, and Plus are compatible with 3 different revisions. Digikey part numbers for replacement parts ...


14

In Poland there was the Commodore & Amiga magazine in 1992-1995. In it's 7th number (July '92, pages 22-23) there was an article on how to build your own power supply for C64 written by Jerzy Dudek. There is an archive of this magazine at http://stare.e-gry.net/czasopisma/commodore-amiga. It's in DjVu format. Here is the schema from this article:


13

You have damaged your Spectrum for sure. The first casualty is the 7805 regulator. These normally explode and release a "black smoke of the death" clearly visible, but yours doesn't seem to be the case. It's curious that this component is designed to survive overvoltage and short circuit conditions, but it is very vulnerable to a polarity inversion. The ...


13

How does the C64 get an accurate TOD clock on 50 Hz power? It doesn't, as the Kernal doesn't care for the build in TOD. The Kernal is a quick hack, taken straight from the VC20, operating the clock on interrupt base - like since PET times (as explained on another question about the 6526). If it would care, it could do so by simply handling Bit 7 of CRA (...


12

You are still recommended to wait about 30 seconds when turning a modern computer off and on again. The risk of any damage was very small but not zero. The risk nowadays is probably even smaller due to protection circuitry being present or better than in the '90s. The idea is that you wait enough time for any charge held in capacitors to dissipate. The ...


11

Normally you would just let it sit for a few minutes. While the output capacitors may have some residual charge, the most any one would have is 12 Volts, which isn't really dangerous to your fingers. The input filter capacitor after the full wave rectifier, however, is a more likely threat, but killing the AC input while the power supply is under load will ...


11

Its hard to tell exactly from just that brief description, but I think you're probably referring to the sound of the hard drive head seek (repositioning to different areas of the disk) as data is read from the drive. That's the repetitive ticking you can hear in this video when the Windows 95 splash screen is showing and the OS is being loaded from the hard ...


11

Aside from Cromatix great answer, the thing to consider was difference in power. Typical home microcomputers (like ZX Spectrum or Commodore 64 etc) used power supplies with about 10-30 watts, while IBM PC XT has chunky 130W power supply (which increased to 192W SMPS in IBM AT). That much power requires much more space, and would be quite unwieldy as separate ...


10

It should work just fine -- the PPU times the rendering process based on the clock. The NES doesn't directly use the 9V AC from the power supply; the power supply circuit converts it to 5V DC with a rectifier and voltage regulator. I'm using a DC adapter with my NES without problems.


10

Anecdotal answer, because I don't feel like googling for lots of schematics: Most AT mainboards only use +5V. In some cases, +12V is used for miscelleanous stuff, I remember an auto-voltage mainboard where the +5V/+3.45V switch for the 80486 processor used the voltage detection pin, and controlled the +5V Vcc connection using a FET that got its gate drive ...


9

Yes, you can use a standard ATX power supply. Do not just match the wire colors. Look up the pinouts. Then (preferably) verify them yourself with a multimeter before wiring things up. In order to turn on the ATX PSU you will have to short PS_ON with COM (ground). You can wire up a momentary switch for this purpose. ATX pinout: https://en.m.wikipedia.org/...


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